Spirastrella coccinea is a thin encrusting sponge, less than 10 mm (0.4 in) thick, forming patches of a square metre or more, covering the substrate.

[2] Sponges in shallow water are orangish-red while those at greater depths are red or pink, sometimes with white specks near the oscula.

The spicules that stiffen the sponge and form the skeleton are tylostyles, rods with one end pointed and the other knobbed, and there are also microscleres in the tissues, but no spongin fibres.

[3] Spirastrella coccinea is found in the Caribbean Sea, the Gulf of Mexico and the tropical western Atlantic Ocean as far south as Brazil.

[5] Since then, five further macrolides, "Sprirastrellolide C to G" have been found in extracts of the sponge, their structures being elucidated by spectroscopic analysis and chemical means.