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.
Seaweed cultivator
A seaweed cultivator is a device which grows seaweed, usually in weekly or bi-weekly cycles. It is not to be confused with people who are seaweed cultivators themselves, usually performing manual cultivation of seaweed using large nets in open waters (mainly in Asian countries).