The flexible stalks may be hidden, covered by the hard shells.
Dozens of off-white plates form two shielding halves around the bulk of the gooeseneck (leaf) barnacle’s body; a tough, rubbery stalk connects it to the rock. A great combination in the gooseneck barnacle’s heavy surf habitat: armor and give.
Water currents or cascades will entice the gooseneck barnacle to gape those shielding halves and extend its ten feathery legs to feed on plankton and detritus in the water. The long slits between the halves are parallel to the main water current.
While well-adapted to wave action, leaf barnacles cannot stand up to scuffing human feet.