What is "macrobenthos"

n. (context biology English) benthic organisms that are big enough to be seen with the naked eye

Macrobenthos consists of the organisms that live at the bottom of a water column and are visible to the naked eye. In some classification schemes, these organisms are larger than 1 mm; in another, the smallest dimension must be at least 0.5 mm. They include polychaete worms, pelecypods, anthozoans, echinoderms, sponges, ascidians, crustaceans.

A visual examination of macroorganisms at the bottom of an aquatic ecosystem can be a good indicator of water quality.

Image:Posidonia oceanica Portofino 02.jpg| Seagrass. Image:Nerr0878.jpg| Echinoderms Image:Scheibenanemonen (Actinodiscus spec).jpg|Stony corals Image:Seasquirt.jpg|A sea squirt being used as a substrate for a nudibranch's egg spiral.