[2][1] It is found in freshwater habitats around the world, preferably with low levels of pollution;[1] it is typically attached to solid substrates.

[3] Microthamnion consists of a microscopic, branched system of erect filaments.

[1][3] Reproduction occurs asexually via the formation of bottle-shaped zoospores, which are formed in vegetative cells that develop into sporangia.

[5] Microthamnion was first described by Carl Nägeli in 1849 in Friedrich Traugott Kützing's work Species algarum.

[4] The species-level taxonomy of this genus is unclear, since individuals display a wide range of morphological variation.