Micraster
Micraster is an extinct genus of echinoids from the Late Cretaceous to the early Eocene. 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.
In the classic text The Science of Life, H. G. Wells, Julian Huxley and G. P. Wells use Micraster as an example of a fossil whose continuous evolution can be traced over some 10 million years through 450–500 feet of chalk beds of the Late Cretaceous. They point out:
Species
Micraster quebrada, 2023 †Micraster norfolkensis, 2012 †Micraster burgiensis, 1935 †Micraster coravium, 1959 †Micraster corangium, 1778 †Micraster decipiens 1878 †Micraster depressus, 1937 †Micraster desori, 1926 †Micraster elevatus, 1949 †Micraster ernsti, 2024 †Micraster leskei, 1855 †Micraster piriformis, 1927 †Micraster subglobosus, 1959 †Micraster trangahyensis, 1936 †Micraster turonensis 1878 †Micraster uddeni, 1953 †Micraster vistulensis, 1950 †