Scientists researching the Gulf of Mexico have found an underwater mass of dead biological material that appears to be growing as microscopic algae and bacteria get trapped and die. The blob is at least three feet (90 cm) thick and spans two-thirds of a mile (1 mile = 1 609 meters) parallel to the coast just off the Florida Panhandle, within the site of Perdido Key. The blob smells like rotten eggs and feels similar to jelly.

The researchers have been unable to determine how the blob was formed, where it comes from or where it will go. Tests show that the material is nearly 100% biological and less than a year old. It is also clear that tiny organisms have gotten stuck in the sticky blob and died. Tests carried out by the researchers also showed that the blob has no connection to land.

It seems to be a combination of algae and bacteria,” says David Hollander, a chemical oceanographer with the University of South Florida. According to Hollander, the substance is toxic and “extraordinarily sticky”.

Scientists are not ruling out a connection to last years’ Deepwater Horizon disaster, but so far none of the tests have shown any sign of oil.

Researchers encountered the blob for the first time in December as they were searching for oily sediments on the sea floor. They did find such sediments, but they also got a tip about something weird floating around roughly half a mile from Perdido Pass and this caused them to change their plans and head over to the area to investigate.

The environment where the blob can be found is a relatively pristine sloping shelf. Normally, wave action will sweep away any sediments here.

Hollander and his team are planning to return to the blob within a few weeks to gather more samples, since they were unable to get any material from the bottom of the blob during their last visit. They will also try to map out the entire blob to be able to see exactly how big it is.