Sea Beans.
DID YOU KNOW THERE ARE THINGS CALLED SEA BEANS???
https://i.pinimg.com/originals/14/e7/f8/14e7f8abdf0d6c9613c7d2d7b5b36e5e.jpg
There are rain/tropical forests all around the world where seeds fall into rivers or are swept into waterways during flooding/storms. And most of these seeds get washed up on the banks of the rivers they fell into.
But...some of them end up floating down the rivers until they reach the ocean. They then float like tiny boats sometimes for as long as 30ish years on ocean currents that drop them off on beaches around the world.
There are all different kinds of sea beans and some of the rarer ones have really cool patterns and colors. But the really cool thing is that you can germinate/plant them (their hard shell usually protects them from too much damage)!
Sea Beans are a category of smaller "Drift Seeds."
Coconuts are a good example of a larger drift seed.