What is "micraster"

Micraster \Mi*cras"ter\, n. [NL., fr. Gr. mikro`s small + ? star.] (Paleon.) A genus of sea urchins, similar to Spatangus, abounding in the chalk formation; -- from the starlike disposal of the ambulacral furrows.

n. (context paleontology English) Any of the extinct genus (taxlink Micraster genus) of infaunal echinoids.

Micraster is an extinct genus of echinoid from the Late Cretaceous to Paleocene. Its remains have been found in Africa, Antarctica, Europe, and North America. Micraster was an infaunal echinoid living in a burrow below the sediment surface. The test is clearly bilateral and there is a deep anterior groove to take in water containing organic particles to the mouth. The tube feet keep a supply of nutrient-laden water moving into the burrow. The anus has a waste tube behind it.