Agar
From Genetics Wiki
Agar is isolated from some red algae species such as Gelidium amansii and Gracilaria species.
Links
http://www.fao.org/docrep/field/009/ag156e/AG156E01.htm
http://www.fao.org/docrep/006/y4765e/y4765e05.htm
https://dlnr.hawaii.gov/hisc/info/invasive-species-profiles/gorilla-ogo/