A. Scanning electron micrographs of microscleres (courtesy of H.M. Reiswig), left: a hexaster, the diagnostic spicule type of subclass Hexasterophora (scale bar = 10 µm), right: an amphidisc, the diagnostic spicule type of subclass Amphidiscophora (scale bar = 100 µm); B. "Hyalonema" sp., an amphidiscophoran (Amphidiscosida: Hyalonematidae), Bahamas; C. "Atlantisella" sp., a lyssacine hexasterophoran (Lyssacinosida: Euplectellidae), Galapagos Islands; D. "Lefroyella decora", a dictyonal hexasterophoran (“Hexactinosida”: Sceptrulophora: Euretidae), Bahamas. B–D courtesy of Harbor Branch Oceanographic Institute (Ft. Pierce, Florida, U S A), images taken from manned submersible Johnson-Sea-Link II.