exposed to the sun in Nova Scotia, Canada]] coast]] For the band, see; Seaweed For the rock musician, see; Seaweed Seaweeds are any of a large number of marine benthic algae. They are macroscopic and multicellular, in contrast with most other algae. Smith, G.M. 1944. Marine Algae of the Monterey Peninsula, California. Stanford Univ., 2nd Edition. Seaweeds are often found in the seashore biome. Taxonomy Seaweeds consist of several groups of multicellular algae: the red algae, green algae, and brown algae. As these three groups are not thought to have a common multicellular ancestor, the seaweeds are a paraphyletic group. In addition, tuft-forming bluegreen algae (Cyanobacteria) are sometimes considered as seaweeds. Seaweeds are popularly described as plants, but only red and green algae belong to the kingdom Plantae. They should not be confused