Where have all the coconut heads gone? If such questions keep you up at night, puzzling over the disappearance of the Florida tourist trinket -- roll over. Alex's Gift Shop in Dania Beach has enough coconut heads to crowd your next luau, as well as shell-encrusted jewelry boxes, figurines, and shell-lined mirrors, placemats featuring Fort Lauderdale scenes, plastic alligators, crabs, and sea turtles. They also sell some really large and spectacular shells capable of bringing littoral splendor to any living room. Some of these you'd never find on a Florida beach, and some have grown scarce, including giant clam, horse and queen conch, chambered Nautilus, and large chunks of coral. Prices range from one cent for an apple-blossom shell to as much as $2000 for a Giga clam.