In Arctic and Antarctic ecology, a hypolith is a photosynthetic organism that lives underneath rocks in climatically extreme deserts such as Cornwallis Island and Devon Island in the Canadian high Arctic. underneath rocks in climatically extreme deserts such as Cornwallis Island and Devon Island in the Canadian high Arctic. The community itself is the hypolithon. The most signifinicant characteristic is that Hypolithons are protected from harsh ultraviolet radiation and wind scouring by their rock, which can also trap moisture.