blastoid,a.andn.|ˈblæstɔɪd|[f.mod.L. Blastoidea,f.Gr.βλαστός sprout, germ + εἶδος form: see blasto- and -oid.]A.adj.Of or belonging to the Blastoidea, a group of fossil echinoderms.B.n.An echinoderm of this group.1876Q.Jrnl.Geol.Soc.XXXII. 112The Blastoid affinities of Astrocrinites (=Zygocrinus) have been pointed out.1882GeikieText-bk.Geol.iv. ii. 722The blastoids or pentremites, which now took the place in the Carboniferous waters that in Silurian times had been filled by the Cystideans.1914Brit.Mus.Return 202Newly-described Blastoids from Somerset.1962D. NicholsEchinoderms viii. 96Tubercles have not been found in cystoids, blastoids and heterosteles.Ibid.xii. 149The steganoblastidae are superficially blastoid-like.