Starfish are awesome creatures. To check to make sure they are not alive, pick one up and put it in the palm of your hand. The starfish should be a little stiff. You'll feel an alive starfish on your palm as it tries to suction itself to your palm. The feeling is soft and gentle but you'll want to rescue it and return it to the sea.
I've been in love with having sand between my toes since I was a teenager taking the ferry across the bay to arrive at Presque Isle State Park (aka The Peninsula) in Erie, PA.