Substrate is the earthy material that forms or collects at the bottom of an aquatic habitat.
It is made of sediments that may consist of: Stream substrate can affect the life found within the stream habitat.
Muddy streams generally have more sediment in the water, reducing clarity.
Marine substrate can be classified geologically as well.
Mollusks and clams that live in areas with substrate, and need them to survive, use their silky byssal threads to cling to it.