Sinking to or lying on the bottom; living on or near the bottom and feeding on benthic organisms.

Grayish piles of organic compounds that accumulate in the Aquarium. Commonly will contain fish wastes, fragments of rock, leftover food, among other things. Usually detritus will accumulate in low water flow areas, sumps, etc.

Animals that eat detritus. Common detritvores are urchins, stars, hermits, etc.

A diatom is any of a class of microscopic one-celled algae having walls of silica consisting of two interlocking valves.

An organism that is active during the day, and sleeping at night.

The fin directly on the top of the body (it's the fin that sticks out of the water when you see a shark). Some fish have two dorsal fins one directly behind the other.