The ocean gives, and the ocean takes away. Or is it the other way around? Ever since humans invented the boat, they've wrecked, capsized, or lost their cargo in the sea, and whatever was inside can ride the currents until it lands in some far-off shore, maybe soon, maybe decades later. And some of that cargo is pretty strange.
Some of the stuff that washes up is natural, as in unidentified sea creatures, and some are legends from long ago. Read about 15 odd beach finds at Cracked.