Ancient mystery worm found to have surprise eyes and teeth

Hallucigenia sparsa, one of most common creatures 500m years ago, had previously baffled scientists as an anatomical misfit without distinguishable head or rear

Nature has produced many oddities, but an ancient creature resembling a prickly sea worm is one of the few to have left scientists so baffled they were unable to distinguish its head from its the rear.

The organism, called hallucigenia sparsa, was once one of the world's most common creatures, but its unearthly appearance has led it to be regarded as an evolutionary misfit - not least because this basic anatomical question has remained unresolved.