Corallimorph anemone (Corallimorphus sp.)
The corallimorph anemone or mushroom anemones are similar to sea anemones. They lack a calcareous skeleton but also lack the long feeding tentacles that a sea anemone has. They often have a flattened oral disc with a smooth, bumpy, or fuzzy appearance. Mushroom corals have symbiotic zooxanthellae in their tissues. They come in a wide variety of colors and can be solid, spotted, or striped. Neptune Canada’s guide included it in the “sea anemone” category because of similarity, but it belongs to another order: Corallimorpharia.
Reference:
Marine Life Field Guide (Neptune Canada)