The thallus grows from a discoid holdfast to a length of about 23 centimetres (9.1 in).

[2] The branches are hollow, soft and twisted, dark reddish brown in colour which bleach towards the tips, they clearly taper at their junction.

[1] The plants are dioecious (sexes separate) with microscopic spermatangia, carposporangia, and tetrasporangia developing in the surface layer, cruciate.

[1][3] Generally epilithic in rock pools of the littoral zone.

Europe from Russia to Portugal and Canada to United States.