body shaped like flat, long band or lanceolate, comprising two layers of cells in irregular cleavage, entire in edge or wave-like folded. The leaf of its mature body is twisted like a spiral attached on the rock with disc-like appressoria. The body length is normally about 20-50 cm in a width of 1-3 cm, sometimes reaching more than 1 meter if growing in the place with organic contaminants.