Xyloplax medusiformis is a sea daisy, a member of an unusual group of marine taxa belonging to the phylum Echinodermata.

[2] Its generic name derives from the Greek "xylo" meaning wood and its specific name was chosen because its morphology superficially resembles that of a cnidarian medusa.

[3] Specimens of Xyloplax medusiformis were first discovered by accident when a submersible craft was being used to collect samples of wood on the deep sea bed in the South Pacific near New Zealand.

It was found that X. medusiformis was indubitably a member of class Asteroidea and was a sister taxon to Rathbunaster in the order Forcipulatida.

The aboral (upper) surface is covered with flat plates arranged in concentric rings and there are short marginal spines projecting from the periphery.