Shallow marine sediment bottom (Euphotic marine sediment bottom)

Shallow marine sediment bottom is found along the entire Norwegian coast. Simply put, the area is characterized by soft sediment and shallow water. The sediment can consist of, for example, fine-grained clay, sand, gravel and small stones. When the sediment is made up of half-decomposed limestone shells from mussels, sea urchins, snails, and the like, it is called shell sand. The shallow marine sediment bottom extends from the seashore and as far down as the sunlight reaches (15-30 m).

The animals that live in the shallow marine sediment bottom are usually partially or completely buried in the bottom. It is common to find mussels, bristle worms and small crustaceans here. Algae (seaweed) is sparse and often loose on the bottom or attached to small stones and shells. Examples of brown algae commonly found are spiral wrack, Norwegian/knotted kelp and toothed wrack. Among the green algae, grass kelp and sea lettuce can be found.