From Britain to Spain to Denmark, rubbery blocks have recently washed up on beaches, all bearing the same word: Tjipetir. It's still not certain where each block comes from, but a woman who found one while walking her dog in England has a pretty good idea, the BBC reports. After Tracey Williams posted on a Facebook page about her investigation into the matter, two individuals who haven't been publicly identified told her about a Japanese ship sunk 150 miles west of Britain's Scilly Isles during World War I. The Miyazaki Maru carried the blocks, and it has recently been subject to salvage work, resulting in their release, the sources explained. The blocks have their origins in Indonesia, where they get their name from a 19th- and 20th-century rubber plantation in West Java.
The rubber-like stuff—likely a tree gum called gutta-percha—was once used for such diverse purposes as insulating cables and making golf balls. Williams' theory is supported by a British official in charge of the country's wreck laws—the Receiver of Wreck, as she's known. But "many ships would have been carrying gutta-percha, so it's possible that the cargo is coming from more than one source," Williams notes. One of those sources could be the Titanic, which listed such blocks among its cargo, the Daily Mail reports. Interesting pieces of history, but not so appealing to conservationists: "The thing we find most worrying is that this is biodegradable rubber and here it is, 100 years later, in near-perfect condition," says one. (In other weird beach finds, a two-headed dolphin recently washed ashore.)