Plant adaptation
BARNACLES cement to rocks, close their valves so they do not dry out, conical shape
SEA SQUIRTS store water during low tide, soft jelly like bodies (looks like a vegetable but is an animal. has two siphons, one to inhale water the other to exhale water and waste)
SEA WEEDS holds fast to anchor themselves and slimy mucus. (there are other types of seaweeds that has roots to anchor themselves to adapt in the fluctuation of temperature, currents, and salinity of the water.)
* in the event that the limpet is included in the original question.
LIMPET muscular foot, cup shaped shell