Tube feet
Tube feet are used to move, feed and breathe. They are arranged in grooves along the arms. They operate through hydraulic pressure.  They are used to pass food to the oral mouth at the center, and can attach to surfaces. Tube feet allow these animals to stick to the ocean floor and move slowly. A sea star that is overturned simply turns one arm over and attaches it to a solid surface, and levers itself the right way up.