(Forskål, 1775)
Massive; with central mound bearing 10-50 large irregular warts, surrounded by a moat; only peripheral region of bell flexing. Disc wider than high, to ca. 50 cm; varied in shape from filamentous to thick, in some specimens angular, projections, pointed to rounded; peripheral flexible skirt region without marks, grooved radially. Marginal lappets 50-70, rounded, clefts between shallow, forming crenate edge; rhopalia 8, set in from margin. Mouth-arms 4, each forking basally making 8 main groups of branches; much branched, extending slightly beyond disc margin; mouthlets numerous, 10-50 short clubs and long filaments between the branches, filaments up to 2-3 times disc diameter. Radial canals 32 (8 main plus 8 groups of 3), joined peripherally by anastomosing network; no ring canal.
Coloration: exumbrella blue through lilac to mauve, translucent peripherally; mouth-arms brown, short clubs white, filaments colorless. Variation: proportional extent of central exumbrellar region, and shape, size and number of the warts, greatly varied. Related Cotylorhiza (Mediterranean; ? Canaries, possibly Africa south of the equator) lacks exumbrellar projections, dominant coloration yellow.
(After Mayer, 1910; P.F.S. Cornelius, pers. obs.).