Description: Thalli filamentous, erect and finely branched to 7 cms long, but variable. Rhizoidal filaments grow down forming a cortex at the base.

Habitat: Epiphytic and epilithic in mid to low-littoral in rock pools and sublittorally.

Distribution: Widespread and common around the British Isles from the Shetlands to the Channel Islands. Europe: Mediterranean, Azores, Portugal, Atlantic coasts of Spain and France, Baltic Sea, Faroes, Norway and Iceland. Atlantic coast of North America: the records from New Hampshire may involve another species. Further afield: South Africa.

Similar Species: All species of Aglaothamnion and Callithamnion are similar and not easy to identify.

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

iNaturalist: Aglaothamnion hookeri at iNaturalist World Species Observations database.

WoRMS: Aglaothamnion hookeri at World Register of Marine Species. Accepted name: Gaillona hookeri (Dillwyn) Athanasiadis, 2016. AphiaID: 1311368.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Callithamniaceae; Callithamnioideae; Callithamnieae; Aglaothamnion