Description: Thin sheets, up to 3cms across, but smaller typically. Consistently pale yellow. "Yellow, or yellowish orange" (in the Mediterranean). "Deep orange, rarely red". (Amber yellow when dry, pale pink in spirit). Soft. Oscules may not be apparent. Pores in oval pore areas with smooth tissue between. "Oscules dispersed, simple".

Habitat: On rock, stones and bivalve shells, to 300m. Reported on algae and sponges in the Mediterranean. On horizontal rock in clear water.

Distribution: Channel (Roscoff), west coast of England, Mediterranean, Azores.

Distribution Map from NBN: Hymedesmia pansa at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Hymedesmia pansa at iNaturalist World Species Observations database.