This is a sea star. Its full name is the ochre sea star or Pacific sea star. They can be found clinging to wave swept rocks in the intertidal zone. The ochre sea star can be purple, orange, or even dark brown. It eats mussels, barnacles, and other creatures in the intertidal zone.
Clue #1 I am not a rock.
Clue #2 I live in the ocean.
Clue #3 I can grow to be about 14 inches (36 cm) wide.