Mycale laevis (Carter, 1882) Poecilosclerida, Mycalidae Common Name(s): Orange icing sponge, Orange undercoat sponge Growth Form: Thinly to thickly encrusting. Surface: Smooth, porous, covered by a transparent membrane. Distinct canals converging on oscules are visible when the boulder or coral under which it lives is overturned. Color: Orange to yellow, with canals and oscular membrane whitish to transparent. Specimens in dark habitats may be white. Consistency: Fragile, easily torn, although spicule tracts may be slightly tough. Exudate: None. Oscules: Round, elevated by a tall, transparent collar membrane with fine parallel lines; found along the outer edge of the surface accessible to the sponge; often wider than the surrounding tissue. Skeletal Components (Spicules, Fibers): Megascleres are slightly bent rods with 1 abruptly pointed end and 1 blunt or rounded end (style). Microscleres include 1) large and small curved shafts with unequal recurved end plates (anisochela), the large ones often arranged in bouquets or rosettes; 2) large and small C- or S-shapes (sigma), and 3) bundles of hair-like spicules (raphides in trichodragma) abundantly scattered in the tissue. Skeletal Architecture: Incomplete, confused surface meshwork of single megascleres with microscleres scattered between. Interior dominated by ascending, interconnecting, rather irregular thick tracts of megascleres (40-310 μm across) ending in spicule brushes that protrude at the surface. Ecology: Under and lining the edges of plate-like or overhanging stony coral colonies, calcareous worm tubes or boulders on coral reefs and hard bottoms; sometimes modifying the pattern of coral colony growth. Distribution: South Florida, Bahamas and throughout the Caribbean. Notes: Halichondria cf. magniconulosa also forms cryptic encrustations, but does not characteristically protrude along the edges of corals or rock substrates. References: Carter (1882), van Soest (1984), Zea (1987). Similar species: Halichondria cf. magniconulosa