Hallucigenia was long regarded as a bizarre animal. The name derives from the word hallucination, and suggests that scientists could not understand how such a creature could function at all. They thought it was a worm-like animal that stood on stilts in the mud of the ocean floor and had a number of outgrowths on its back.
Hallucigenia upside down, and below right way up. At first, scientists thought that the protective spines on the back were stilt-like legs.
Photo: Jean-Bernard Caron, the Royal Ontario Museum
But later on scientists, including some here at this museum, tried turning the animal upside down. Then they realized that the outgrowths on its back were in fact legs on its underside, and that the stilts were protective spines on its back.
Hallucigenia is related to present-day velvet worms which live among decaying tree trunks and leaves in tropical forests.