These algae live in some of the deepest places and some of the harshest intertidal areas.
You can find delicate red seaweeds washed up on the beach or lining the sides of rockpools.
Some other red seaweeds form a crust under rocks and the shaded sides of rockpools. These plants are hard because they have limestone skeletons. They are called coralline seaweed and can also be pink or purplish. Some sponges also cover rocks. Sponges feel softer. Some coralline seaweeds look like fern fronds.