Seaweed
"Seaweed" is a colloquial term and lacks a formal definition. A seaweed may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. As these three groups do not have a common multicellular ancestor, the seaweed are in a polyphyletic group. In addition, some tuft-forming bluegreen algae (Cyanobacteria) are sometimes considered to be seaweed.
Posidonia australis
Posidonia australis is a species of seagrass that occurs in the southern waters of Australia. It is sometimes referred to as fibreball weed. The marine plant forms large meadows that are considered to be of high importance to the environmental conservation of the region. Balls of decomposing detritus from the foliage of the plant are found along nearby shore-lines.