A giant prehistoric shrimp-like monster which terrorised the oceans more than half a billion years ago has been discovered by scientists.

The fearsome-looking beasts, known as anomalocaridids, grew up to 6ft long and - unlike today's prawns - could bite back, using its razor-sharp teeth to crack open shellfish.

They were already believed to be the largest animals of the 'Cambrian' period which first spawned our complex ecosystem.

While scanning underneath the waters of Lake Michigan for shipwrecks, archeologists found something a lot more interesting than they bargained for, as they discovered a boulder with a prehistoric carving of a mastodon, as well as a series of stones arranged in a Stonehenge-like manner.

At a depth of about 40 feet into Lake Michigan's Grand Traverse Bay, using sonar techniques to look for shipwrecks, archeologists discovered sunken boats and cars and even a Civil War-era pier, but among all these they found this prehistoric surprise, which a trained eye can guess by looking at the sonar scans photos in this article.

"When you see it in the water, you're tempted to say this is absolutely real," said Mark Holley, a professor of underwater archaeology at Northwestern Michigan University College who made the discovery, during a news conference with photos of the boulder on display in 2007. "But that's what we need the experts to come in and verify.

A robot explorer sent through the Great Pyramid of Giza has begun to unveil some of the secrets behind the 4,500-year-old pharaonic mausoleum as it transmitted the first images behind one of its mysterious doors.

The images revealed hieroglyphs written in red paint that have not been seen by human eyes since the construction of the pyramid. The pictures also unveiled new details about two puzzling copper pins embedded in one of the so called "secret doors."

Published in the Annales du Service Des Antiquities de l'Egypte (ASAE), the images of markings and graffiti could unlock the secrets of the monument's puzzling architecture.

"We believe that if these hieroglyphs could be deciphered they could help Egyptologists work out why these mysterious shafts were built," Rob Richardson, the engineer who designed the robot at the University of Leeds, said.

Built for the pharaoh Cheops, also known as Khufu, the Great Pyramid is the last remaining wonder of the ancient world.

The monument is the largest of a family of three pyramids on the Giza plateau, on the outskirts of Cairo, and has long been rumored to have hidden passageways leading to secret chambers.

Archaeologists have long puzzled over the purpose of four narrow shafts deep inside the pyramid since they were first discovered in 1872.

See how current flood compares with epic deluges of past two million years.

This story is part of a special National Geographic News series on global water issues.

As the crest of the Mississippi River flood moves through New Orleans and out to sea this week, peak river levels recorded during the month-long deluge threaten to top even the Great Mississippi Flood of 1927.

The most destructive river flood in U.S. history, the 1927 event moved about 2 million cubic feet (65,000 cubic meters) of water - enough to fill about 26 Olympic-size swimming pools - every second. (See pictures: "Mississippi River at Its Worst.")

"The numbers are still provisional, but [the current flood's peak water discharge] looks to be about the same" as the 1927 flood, said James O'Connor, a hydrologist with the U.S. Geological Survey (USGS).

Still, the 1927 and 2011 Mississippi River floods remain just drops in the bucket compared to other known freshwater "megafloods" around the world, according to O'Connor.

The scientist co-authored a 2004 USGS report that ranked all freshwater floods known to have occurred during the past two million years. The list, which remains largely unchanged since its release, includes only floods that had peak discharges of 3.5 million cubic feet (100,000 cubic meters) a second or more.

The tradition of putting body parts on display is almost as old as religion itself. Reliquaries containing the hands, feet, teeth, and other parts of holy people have been touted around the globe for thousands of years. But 20th-century cultural icons and ancient historical figures? Yeah, those get around too.

While some are proudly on display, many are decidedly better hidden. But with careful planning and a discerning eye, there are some pretty incredible body parts to be seen out there. You just have to know where to look.

Einstein's Brain, University Medical Center, Princeton, New Jersey

All of us have one, some are a lot more developed than others, and Einstein's was incredible. Yep! We're talking about brains.

When Einstein died in 1955, his brain was removed by Thomas Harvey, a doctor working in the Princeton Hospital in New Jersey where the scientist passed away. Harvey thought that careful study of Einstein's brain would help him figure out what made the guy so gosh darn smart. Harvey was not granted permission to remove Einstein's brain, but he did it anyway, which landed him in some pretty hot water. And after Harvey became frighteningly obsessed with the brain and refused to relinquish possession of the specimen, he was fired from the Princeton Hospital and left in shame. But not before stealing the brain.

Harvey left New Jersey and went on a wild scientist goose chase. He traveled to any research facility or lab that agreed to perform tests on the brain. And here's where things really get weird: after a divorce and a downward spiral that brought him across the Midwest, Harvey ended up losing his medical license. His tragic tale ends with a cross-country road trip intended to return Einstein's brain to his granddaughter, only for her to tell him she didn't want it. 40 years later, Harvey returned the brain, in pieces, to the pathology lab in Princeton.

The bits of brain are somewhere in the Princeton Hospital, although we're not sure exactly where. Anyone got any insider info? We'd love to know.

Construction work on a new housing development in Runcorn has unearthed what are thought to be the final remains of the medieval village of Norton.

Around 80 archaeological features have been found at the site near Lodge Farm, off Highgate Close, Norton village, since excavation began at the end of April.

Archaeologists have unearthed shards of pottery they believe date from the 13th and 14th centuries, as well as the footings and post holes of former timber-framed houses close to site of the old village road.

Social landlord Riverside is currently developing the site to provide three new pairs of three-bedroom semi-detached homes. The homes, designed by Croft Goode Architects, will provide sustainable housing for local people and will be made affordable under a shared ownership scheme.

Seventeen lost pyramids are among the buildings identified in a new satellite survey of Egypt.

More than 1,000 tombs and 3,000 ancient settlements were also revealed by looking at infra-red images which show up underground buildings.

Initial excavations have already confirmed some of the findings including of two suspected pyramids.

"To excavate a pyramid is the dream of every archaeologist," says Dr Sarah Parcak.

She has pioneered the work in space archaeology from a Nasa-sponsored laboratory in Birmingham, Alabama and says she was amazed at how much she and her team have found.

"We were very intensely doing this research for over a year. I could see the data as it was emerging, but for me the "A-Ha" moment was when I could step back and look at everything that we'd found and I couldn't believe we could locate so many sites all over Egypt."

The team analysed images from satellites orbiting 700km above the earth, equipped with cameras so powerful they can pin-point objects less than 1m in diameter on the earth's surface.

Infra-red imaging was used to highlight different materials under the surface.

Earlier this year, Linda Azaroff's fourth-grade class received a 2.2-pound (1-kilogram) box containing what one student described as a "clump of dirt."

But this wasn't just any dirt - it was sediment, or matrix, collected from a backyard in Hyde Park, N.Y., in 2000, where a project to deepen a backyard pond uncovered the remains of a mastodon - an extinct elephantlike animal. Working under a deadline, but not wanting to miss any important pieces, excavators carted away about 22,000 pounds (10,000 kg) of matrix from around the bones, more than they could realistically sort through in the years to come.

The excavators turned to citizen scientists volunteering for the Mastodon Matrix Project, which enlists school classes, hobbyists, families and other volunteers scour the matrix from mastodon excavations. Since 2008 alone, more than 3,500 participants from around the U.S. have worked on matrix from Hyde Park.

"One of the huge limiting things form a scientific standpoint is we often don't have the staff time either from interns or scientists themselves to go through all of this stuff," said Carlyn Buckler, an education and outreach associate at the Paleontological Research Institution (PRI), which operates the Mastodon Matrix Project. "The more data we can get, the more complete a picture we will come up with about the environment."

This approach isn't unique; students and other citizen scientists can contribute their time and effort to a variety of projects, from recording road kill to counting stars. In return, volunteers get hands-on experience with science and the chance to contribute to real research projects.

Old square wells of over 600 years old in the northern province of Vinh Phuc are special, for their square shape and are mysterious through tales told by locals.

The wells in Ba Hien, Vinh Phuc, are different from all wells in Vietnam's countryside, since well mouths are in square shape, which are made by four rectangular pieces of rock. These wells are from 4 to 7 meters deep and they are always full with water.

Local people thought that these wells were built by Chinese because the well mouths have Chinese scripts. Recently the local authorities invited experts to examine the wells, and they said that the wells were build by Vietnamese people over 600 years ago.

A castle that was once one of the most important buildings in the North Pennines and the gateway to the Bishop of Durham's great deer park of Stanhope, is now revealing its secrets after centuries as a forgotten ruin.

Fifty volunteers from the North Pennines AONB Partnership's Altogether Archaeology and backed by the Heritage Lottery Fund and English Heritage are busy uncovering the ruins of Westgate Castle in Weardale.

From the 13th until the early 17th century, Westgate Castle served as the 'west gate' into the Bishop of Durham's great deer park, and functioned as an administrative headquarters for the Bishop's extensive estate encompassing the Old Forest of Weardale.

By the mid 17th century it lay in ruins and its masonry was quarried for new buildings.

Paul Frodsham, the North Pennines AONB Partnership's Historic Environment Officer said: "Today, nothing of its masonry survives above ground, but recent geophysical survey suggests that substantial walls survive buried below the surface. We're not aiming to excavate the entire site, but just to uncover a sample of what survives in order to help inform plans for its future".