misidentified as Derbesia marina

Description: Thallus is a hollow, spherical ball with a short stalk; it represents the gametophytic phase in the life cycle of the species. It usually grows to 10 mm (0.4 in) tall, and within the sphere are many peripherally located chloroplasts and nuclei. The sporophytic Derbesia phase forms branching, filamentous tufts only 1 cm (< ½ in) tall. Habitat: This species prefers growing on encrusting coralline algae on semi-exposed coasts in the very low intertidal to subtidal.