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 1 cm (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 (0.4 in) tall. Habitat: This species prefers growing on encrusting coralline algae on semi-exposed coasts in the very low intertidal to subtidal. Similar taxa:: Young stages of Monostroma and Ulvaria.