The bottom sediment of this lake is mainly composed of sand and mud.

He seemed in pain with a stone stuck in his sole.

This sea area is rich in diversity of benthic organisms.

He looked at the palm of his hand and thought about the fate written on it.

He examined the bottom of the box.

A sea otter is a very cute animal that lives in the sea.

In the old days, people were moved by the strength and beauty of the sea lion.

A sea lion is a type of marine animal, and it is very rare.

The sea otter is a rare animal, and its ecology is not well known.

The sea otter is a very rare animal.