Science: Kraken or tree trunk? Mystery blob from the deeps confounds the experts

Is it a dead dinosaur? A rotting shark? The last remains of Mr Blobby? One thing's sure - it's big, smelly and on a Tasmanian beach. Beyond that, says Charles Arthur, Science Editor, nobody seems to want to commit themselves.

Is it animal, vegetable, or mineral? We can at least say that it's not mineral. But for the moment, it is very hard to be any more specific about this huge mass of matter that washed up on Four Mile Beach in Tasmania earlier this week.

Despite the recent disagreement between the BBC and Noel Edmonds, this is not believed to be the corpse of Mr Blobby, sacrificed as an offering to the Gods of Programming. But if you do happen to have lost a twenty- foot, four-tonne, fishy-smelling, fibre-covered object apparently sporting at least six tentacly legs (or leggy tentacles) recently, maybe you could get in touch with the coastguard there.

In the meantime, scientists are puzzling over what this ... Blob could be. In the past, decaying objects that have fetched up on beaches have been identified as rotting whale blubber, which does dehydrate to form leather fibres like those visible in the photograph. However, you don't usually get "legs" or "tentacles" in blubber.

Marine biologists are used to getting asked about strange beached objects. "There is certainly a recurrence of things about 15 to 20 feet long being washed up," said Oliver Crimmen of the Natural History Museum yesterday.

Certainly. Reports have come from as far apart as Scotland, Russia, New Zealand and South Africa, and positive identification (if you can be positive of something so formless) at least back to the 1920s.

"They generally turn out to be rotting basking sharks," explained Mr Crimmen.

Aha! So could the Blob be an ex-shark? "They can grow up to 34 feet, and rot down to something like a sea monster," said Mr Crimmen. "Of course, whales can too ... and elephant seals ... and squids.."

Yes, but what about this one? "Hmm. Well, judging from the photos, and what they show of the `legs' and `hair' - well, they don't add up to the decomposition of any known organism. We haven't ascertained yet even whether it's an animal. The fact that it is reported to smell fishy doesn't mean much - any marine thing with sediment and weed is going to smell. What we really need is some clue about what's inside."

Scientists in Tasmania are reported to be planning DNA tests on their mysterious lump. Mr Crimmen reckons though that this is "rather like doing a DNA test on a corpse before you've checked its pockets". He suggests that the first step is to look for any bones or other skeletal tissue. Although from its appearance he reckons it has been rotting in the water for "several weeks", even the cartilage of a basking shark will survive, especially the spine - and the picture does seem to show a spine curving away (at the top right).

The most exciting possibility would be if this is the carcass of a plesiosaur, a dinosaur which had a long neck and paddle-like limbs. But to be sure, someone has to poke it with a stick and find some bones. The best efforts in Tasmania haven't turned any up yet.

And in the end it might all turn out not to be an animal at all. "That fibrous matter could mean ... well, we can't rule out that it's not the bole of a mangrove tree," said Mr Crimmen. "But when I showed it to a botanist he didn't recognise it." Clearly, he's in good company.