Back in 2012 it was reported that rubber blocks were washing up in the UK and northern Europe with the word Tjipetir engraved on it. Titanic was suggested as the source but Tracey Williams of Newquay, Cornwall possibly has determined the source BBC News is reporting. These rubber blocks were gutta-percha from an Indonesian rubber plantation named Tjipetir and were cargo on Titanic. But Williams thinks after charting where the blocks have been found and learning information from two sources that it is from the wreck of a Japanese cargo ship sunk in World War 1. Specifically the Miyazaki Maru which was sunk 150 miles west of the Isles of Scilly.
She learned that during the salvage large amounts of gutta-percha and rubber bales were released from the ship’s hold. And of course they are picked up by the current and tossed around in the ocean until it lands on a beach somewhere. It turns out that the Miyazaki Maru was sunk by the same U-Boat captain who sank the Lusitania in 1915–Walther Schwieger who was one of Germany’s top U-Boat captains during the war. He died in 1917 when his U-Boat struck a British mine while being chased by HMS Stonecrop.
It is speculated that these rubber blocks may be washing up on UK and northern Europe beaches for years to come. It is possible there is more than one source of these blocks as many ships carrying them were sunk during the war. And there still is the possibility some might be from Titanic.
Source: Tjipetir Mystery: Why Are Rubber-Like Blocks Washing Up On Beaches?(30 Nov 2014,BBC)