The new organisms are multicellular but mostly non-symmetrical, with a dense layer of gelatinous material between the outer skin cell and inner stomach cell layers.
The researchers did find some similarities to other animal groupings, such as the Cnidaria - the phylum that comprises corals and jellyfish - and the Ctenophora, which includes the marine organisms known as comb jellies. But the new organisms did not fulfil all the criteria required for inclusion in either of those categories.