Placopsis antarctica

Placopsis antarctica is a species of crustose lichen in the family Trapeliaceae. It is found only in Antarctica, where it forms pale-coloured, circular patches on rock surfaces, typically 1–3 cm (3⁄8–1+3⁄16 in) across, with distinctive finger-like projections that break down into powdery structures. The lichen contains both green algae and blue-green algae (cyanobacteria) as partners, allowing it to both photosynthesise and convert nitrogen from the air into a form that can be used by other organisms. These circular patches can occasionally grow up to 6 cm (2+3⁄8 in) in diameter, with edges that show neat, fan-like folds and can appear either swollen or slightly flattened. First described by scientists in 2005, P. antarctica grows on rocks in ice-free areas of the South Orkney Islands, South Shetland Islands, and Antarctic Peninsula, from near sea level up to 550 m (1,800 ft) in elevation. It is one of the first organisms to colonise areas newly exposed by retreating glaciers, helping ......read more on Wikipedia.