Halidrys siliquosa is a large marine brown algae.

Halidrys siliquosa is a large brown alga growing to a length of 120 centimetres (47 in).

Air bladders occur and are oblong and pointed.

[1] The plants are hermaphroditic,[2] bearing bisexual conceptacles appearing as pods on stalks at the end of branches.

[1] Generally found around Ireland, Great Britain - including Shetland and the Isle of Man.