Tribrachidium was a strange genus of ediacara which has been found in Russia, Ukraine, and Australia.
Tribrachidium has been described as a member of many groups. It probably lived on the bottom of the ocean filtering food. Like many animals from the Ediacaran Period, Tribrachidium was mysterious and little is known about it.
Tribrachidium had trilateral symmetry, which means its three sides were alike. Tribrachidium's three arms were possibly hollow and could inflate and deflate themselves, possibly to move up and down in the water. It was about 2" or 5 cm.
Tribrachidium is the only animal that has been discovered so far that is trilaterally symmetrical. So Tribrachidium may have been in its own group with no descendants.