So called "Sea Beans" (also known as "Drift Seeds") are the seeds of tropical trees and vines which have fallen from their parent plant into into a waterway such as a river and ultimately made their way to the sea. Being buoyant, the seeds are then dispersed by oceanic currents - sometimes thousands of miles (see: http://www.seabean.com). Although not uncommon on northeast Florida beaches, "Sea Beans" are more often found after northeasters of other rough seas. The "Sea Heart" [center below - of the Monkey Ladder Vine (Entada gigas)] is  the most common seed found locally.