- The definition of a psammon is a group of microorganisms that live in between grains of sand in the water.
An example of a psammon is a group of these creatures living on a seashore.
psammon definition by Webster's New World
Ecol. a group of those microorganisms that live in the water held between sand grains in waterlogged sands
Origin: Modern Latin ; from Classical Greek psammos, sand