The Collaborative International Dictionary of English v.0.48:

Blastoidea \Blas*toid"e*a\, n. pl. [NL., fr. Gr. blasto`s sprout
   + -oid.] (Zool.)
   One of the divisions of Crinoidea found fossil in paleozoic
   rocks; pentremites. They are so named on account of their
   budlike form.
   [1913 Webster]