Florideophyceae is a class of exclusively multicellular red algae.

[3][4] They were once thought to be the only algae to bear pit connections,[5] but these have since been found in the filamentous stage of the Bangiaceae.

[6] In the subclass Nemaliophycidae there are three orders, Balbianiales, Batrachospermales, and Thoreales, which lives exclusively in freshwater.

[8] According to molecular clock analysis, Florideophyceae diverged from other red algae about 943 (817–1,049) million years ago.

508 (442–580) mya the split between Ahnfeltiophycidae and Rhodymeniophycidae occurred.