ClipArt ETC
"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec, Ectoderm; en, endoderm; mg, mesogloea; m, m, mesenteries; s, septum; b, basal plate formed of ellipsoids of carbonate of lime secreted by the basal ectoderm; ep, epitheca." — The Encyclopedia Britannica, 1910

Astroides Calicularis

"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec,…