If you happen to find yourself strolling on the beach in Cornwall, you might find some man-made detritus along with the expected array of shells and seaweed and sand. You might find some diving flippers. Or a life preserver. Or a spear gun.
The items will likely be made of plastic. They'll also, likely, be tiny. They'll also, likely, be adorable. Because they'll likely be Legos.
Seafaring bits of Legoland, the BBC explains, have been a regular presence on the Cornish coast for more than a decade—a combination of environmental threat and cultural oddity that also offers a lesson in the still-mysterious workings of ocean currents.
It started in 1997. On February 13 of that year, a rogue wave hit the New York-bound cargo ship Tokio Express while it was only 20 miles off Land's End, on Britain's southwest coast. The ship stayed afloat; some of its cargo, however—62 shipping containers—were thrown overboard as the vessel pitched. One of these containers contained Legos. Tons of Legos—many of them, because of course, nautical-themed. There were toy kits that included plastic aquanauts. And spear guns (13,000 of them). And life preservers (26,600). And scuba tanks (97,500). And octopi (4,200).
In all, that day in 1997, exactly 4,756,940 pieces of Lego sank to the bottom of the sea. But they didn't stay submerged. Or, at least, they didn't all stay submerged. One container opened; its contents billowed out into the Atlantic. "No one knows exactly what happened next," reporter Mario Cacciottolo notes, "or even what was in the other 61 containers, but shortly after that some of those Lego pieces began washing up in both the north and south coasts of Cornwall." And they're still coming in today.
For most sea debris, the trip from Land's End to Florida takes, all told, about three years. Given that it's been nearly two decades since the wave hit the Tokio Express, and given as well that Legos make for light travelers, you'd think that some of the ship's plastic booty would have made it to the U.S. "But," Cacciottolo writes, "there isn't any proof that it has arrived as yet."
It hasn't arrived anywhere, that is, but Cornwall. There's something about that stretch of coast, and about the waters that lead to it, that make it a popular end point for the man-made objects that sail the seas. More than 20 years ago, there was another container spill in the area, this one involving cigarette lighters. And those lighters are still washing up on the Cornish coast. Which is a reminder that the ocean's currents can be as mysterious as they are powerful. "Tracking currents is like tracking ghosts—you can't see them," the oceanographer Curtis Ebbesmeyer told Cacciottolo. "You can only see where flotsam started and where it ended up."
This story originally appeared on The Atlantic.