Dinocochlea

Dinocochlea ingens is a trace fossil specimen held in the Natural History Museum of London.

It is a symmetrical helicospiral several metres in length that was famously unexplained until shown in 2009 to be a concretion formed around the burrow of a worm.

[1] Found in 1921 in the Wealden area of Sussex in England during construction of an arterial road, Dinocochlea was originally presumed to be a fossilised gastropod shell.

[2] This name also gave rise to a second theory on the origin of the object - that it is a coprolite (fossilized animal dung).

The coprolite theory is also considered incorrect on the basis that partially digested organic material which would normally remain in the dung was not present.