Potato Sponge
© Cathy Hopkins, Daily PressA single dislodged potato sponge floats near the mouth of the York River following Hurricane Irene.

And you thought Hurricane Irene was done.

Beachgoers and boaters have reported finding mysterious gray blobs, some as large as a soccer ball, from Virginia to New York.

"They're pretty disgusting looking," said Cathy Hopkins of Hampton, who spotted dozens of the podlike orbs near the mouth of the Poquoson River

So, what are these UFOs - unfamiliar fishy organisms?

"They're potato sponges," said Emmett Duffy, a professor at the Virginia Institute of Marine Science in Gloucester Point.

The sponges - one variety of thousands worldwide - inhabit the sandy bottoms of shallow coastal waterways, Duffy said. Like oysters, they filter microscopic food from seawater.

They typically remain burrowed underwater unless something violent, such as a hurricane, forces them to the surface.

Irene barreled through the lower Chesapeake Bay two weeks ago with sustained winds exceeding 70 mph. It created large waves and current changes that moved the previously static sponges.

They have since been spotted throughout Hampton Roads, particularly in Mobjack Bay and the York and Poquoson rivers, said VIMS spokesman David Malmquist.

While not poisonous, the sponges can irritate the skin and eyes if touched, Malmquist said. They also produce unpleasant odors.

Because of their porous bodies, the sponges can become clogged with storm debris and no longer able to filter feed. In such cases, they often die and start to smell as they decay, Malmquist said.

While not common, there have been reports of potato sponge sightings after previous storms. Hundreds washed ashore at Buckroe Beach in Hampton after Tropical Storm Hanna in 2008.