He phoned the city council, who investigated yesterday.

It took photos and concluded it was probably caused by a flock of birds.

There had been talk that it may be due to the metal bird in the sky.

However, Palmerston North Airport manager Garry Goodman soon put an end to that theory and said it is "very unlikely" to have come from a commercial aircraft.

"Aircraft are pressurised.

"If it wasn't, this would create an emergency leak, which is a major concern.".

Any problem with an aircraft's pressure system would be picked up in a pre-flight check, Mr Goodman said.

"The chances of the faecal matter coming from a plane is negligible."

City top-dressing pilot Pete Harding said it probably didn't come from a small plane carrying fertiliser either.

"It was too windy to fly on Monday. Most of the fertiliser we drop is white and is used by the time we fly home."

Mr Harding also said top-dressing planes rarely flew over residential areas.

Civil Aviation Authority safety adviser Ross St George agreed and says when stories of planes losing their load surfaced a few years ago, they led to a "spate of reports" around New Zealand.

Faecal matter sprayed on a house in Wellington was tested and found it to contain grass seed.

There was no chemical components that are found in aeroplane toilets, Mr St George said.

"If any was to escape it would freeze to the outside of the plane."

Mr St George said said the great metal bird in the sky can rest easy, while recommending the "poo from the sky" is from a flock of birds and nothing else.

Mystery aside, Mr Blumenthal's dad Rex, has volunteered to wash the muck off with a water blaster later this week.

Archeologists say a culture centered in Teotihuacan, known as the City of the Gods, dominated Mesoamerica for hundreds of years during the first millennium. It is unclear what led to the society's collapse.

"We have this incredible ancient site and from that site we can project contemporary content," Srinija Srinivasan, Yahoo's editor in chief, told Reuters. "What is new is the ability to capture this information in such scale."

In the 1970s, astronomer Carl Sagan compiled a record with sounds and images, including a mariachi band and greetings in an ancient Sumerian language, to portray the diversity of life and culture on Earth.

His record was sent out with the Voyager spacecraft in the hope that extraterrestrial life forms would eventually find it.