Eldonioid

Eldonioids or velumbrellids are an extinct clade of disc-shaped cambroernids, the Eldonioidea (or Velumbrellida), which lived in the early to middle Paleozoic (Cambrian to Devonian). The terms "eldonioid" and "eldoniid" have been used somewhat informally and interchangeably, but technically refer to members of the class Eldonioidea and the family Eldoniidae, respectively. The lifestyle of eldonioids is still an unresolved question; some authors reconstruct eldonioids as free-floating planktonic predators similar to jellyfish, while others argue that they were passive detritivores, embedded within the seabed for much of their life.