Crustose reef-forming red algae (family Corallinaceae) that are abundant in post-Jurassic geologic strata and are represented by numerous recent forms growing chiefly on rocks and other algae.
Plants calcified, lacking genicula, entirely pseudoparenchymatous; encrusting to warty, lumpy or fruticose; epigenous and growing partially to completely attached to the surface of various substrates (e.g. algae, molluscs, rock), or growing unattached and free-living as rhodoliths; haustoria unknown.
Thallus organization generally dorsiventral in crustose portions but more or less radial in branches; thallus construction monomerous throughout, consisting of a single system of branched laterally coherent filaments that contribute to a ventral or central core and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface; coaxial growth (in which cells of adjacent filaments in core region are aligned in arching tiers) apparently not recorded. Most filaments usually terminating at the thallus surface in epithallial cells (generally one per filament); outermost walls of epithallial cells flattened with flared corners; cell elongation occurring mainly within actively dividing subepithallial initials that are usually as long as or longer than their immediate inward derivatives. Cells of adjacent filaments linked by fusions; secondary pit-connections unknown.

http://www.algaebase.org/search/genus/detail/?genus_id=96