About Petrosia ficiformis (Poiret, 1789)
Petrosia ficiformis (Poiret, 1789) is most often purple-brown, a color it gets from a symbiotic relationship with photosynthetic cyanobacteria. When growing in areas with no light, this species can be white instead. It has a compact, hard texture, and its spherical oscula are spread irregularly across its surface. This species is native to the Mediterranean Sea and the adjacent eastern Atlantic Ocean. It grows on rocks, inside caves, and within rock crevasses, and typically occurs at depths greater than 5 meters (16 feet).
