Family Description:
Tetrasporangia are terminal and are usually tetrahedrally divided. The carpogonial branch is three cells long.

Species description:
This dark red alga is loosely branched and up to 10 cm (4 in) tall. Unlike the Sea Belly, the hollow parts of its branches do not have transverse diaphragms internally. Spermatia are formed on the surfaces of the branches, while only specialized branchlets bear the cystocarps, which look like pimples raised above the surfaces of the branch tips.

Source:  North Pacific Seaweeds