Over 100
Ikaria fossils have been found. These are simple imprints resembling a small grain of
rice (from 1.9 to 6.7 mm in length), slightly thickening to one end. The "anterior"/"posterior" differentiation may indicate that
Ikaria was a
bilaterally symmetrical animal. No other details of
Ikaria anatomy were found on its fossils. On the same sandstone bed there are numerous
trace fossils of the type
Helminthoidichnites. The animal that produced such traces moved or burrowed through thin layers of well-oxygenated
sand on the
ocean floor as it sought sustenance and appeared to show sensory and seeking behaviour, turning as it moved. It is thought to have moved by
peristalsis, constricting muscles against the animal's
hydrostatic skeleton, and may have possessed a
coelom, mouth, anus, and through-
gut, in a similar way to a worm. The authors of the
Ikaria description find that the size and
morphology of
Ikaria match predictions for the producer of the trace fossil
Helminthoidichnites. At least one of the fossils of
Ikaria identified in the study was found in close proximity to
Helminthoidichnites, which the discoverers attribute to vertical motion of the organism through sediment before its death - noting that due to differing preservation methods it is unlikely that both trace and body fossil could otherwise form simultaneously. However, this does not entirely remove the possibility that the association of
Ikaria with
Helminthoidichnites is erroneous. == Significance ==