On a miserable, drizzly day in late June, Hayley Hardstaff, a marine biologist, took a walk along Portwrinkle Beach in Cornwall, England, and discovered a dragon. It was a Lego piece — black, plastic and missing its upper jaw.

Ms. Hardstaff, who grew up in Cornwall, had a long history of finding Lego pieces. As a child there, she collected them from the beach, puzzled about why so many children were forgetting their toys.

By the time she went walking last June, she knew much more, and quickly recognized the scaly head and neck poking out of the sand, “its entire dragonhood on display.”

Ms. Hardstaff had found yet another tiny artifact of one of history’s oddest maritime mishaps.

In 1997, nearly five million Lego pieces — including 33,427 black dragons — were packed in a shipping container when a rogue wave hit the Tokio Express, a cargo ship hauling the toys and other goods. The ship, which had been traveling to New York from Rotterdam, the Netherlands, nearly capsized, and it lost all 62 of its shipping containers — an event known as the Great Lego Spill.

In a whimsical twist, many of the pieces were nautically themed. It was arguably the single largest toy-related environmental disaster that we know of, experts say, and people are still finding pieces 27 years later.