Penicillus

Genus consisting of a single or slightly flattened stipe terminating in a cluster or tuft of loose, tangled filaments; stalk anchored to substrate with mass of rhizoids; the head or terminal filaments become calcified with age. Found in bays and on sandy bottoms.

Penicillus dumetosus

Species 10 cm high or less (occasionally to 15 cm); stalk irregular and somewhat flattened; head tapers gradually down to stalk. Filaments to 0.8 mm in diameter; may be calcified at base, but usually not at ends. In well protected locations, on sandy bottoms; found throughout the year with Halimeda and Udotea.