Description: Minute, as small spots on other algae 1 - 5 mm in diameter. Consisting of a monostromatic base with a densely packed erect filaments several cells long.

Habitat: Very rare. Epiphytic on Palmaria palmata and Laminaria and other algae in the low littoral and upper sublittoral.

Distribution: Records from scattered sites around the British Isles. Europe: Spain, France, Baltic Sea, Norway, Faeroes, Sweden, Iceland. Greenland. Atlantic coast of North America: Canada, Massachusetts, Rhode Island and Connecticut.

Similar Species: There are other small algae appearing as spots or stain-like patches. All difficult to identify and require microscopic examination.

Distribution Map from NBN: Chilionema foecundum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Chilionema foecundum at iNaturalist World Species Observations database.

WoRMS: Chilionema foecundum at World Register of Marine Species.