The Micropygidae form a family of
sea urchins
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
within the Diadematoida order of echinoderms. The family contains two living species of the genus ''Micropyga'' and one, ''Kierechinus'', known only from
fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
. Morphologically, they are quite flat and have short, sharp spines, which are close to each other. They occur in the Indian and Pacific Oceans.
Diadematoida
Echinoderm families
{{Echinoidea-stub