Mysterious items washing up on beaches have always intrigued beachgoers and sparked speculation about their origins. From strange metal balls to unique phone designs, these objects can reveal unexpected stories. One recent incident occurred on a beach in Western Australia, where a cylindrical object measuring approximately 2.5m (8.2ft) wide and 2.5-3m (8.2-9.8ft) long, with a dome-like cap, left locals puzzled. Authorities are investigating the item, and initial speculation suggested it could be part of a space rocket’s fuel tank. However, Reddit users quickly identified it as part of India’s Polar Satellite Launch Vehicle (PSLV).

Earlier this year, another intriguing object, a nearly perfect 1.5m-wide (5ft) sphere, washed up on the coast of Japan near Hamamatsu. This sparked widespread speculation about its nature, although it was determined not to be an explosive mine or surveillance device. Similar incidents have occurred in the past, such as when a giant Christmas bauble was mistaken for an unexploded device on the Thames in London in 2019.

Unexplained items washing up on beaches are not uncommon. In recent years, beachcombers have discovered various intriguing objects. These include a 24m-long (84ft) wood and metal structure in Florida, initially speculated to be a barrier, old pier, or spectator seats from a Nascar race, but later identified as a shipwreck by archaeologists. For 35 years, residents of a Brittany coast found Garfield-themed landline telephones washing up, with the mystery finally solved when a lost shipping container was located. Other discoveries include rubbery blocks engraved with the word “Tjipeter” appearing all over Europe a decade ago, a large foam object in South Carolina labeled as “space junk,” and various far-flung items found on British beaches, showcasing the endurance and long-distance travel of materials in the ocean.

Researchers can sometimes determine the origin of washed-up objects by studying maps of ocean currents, which they have been meticulously building since the 1980s. Drifting buoys equipped with location-tracking capabilities have played a crucial role in collecting data on ocean currents. Additionally, discarded items like printer ink cartridges, syringes, golf balls, business cards, and drinks bottles have been used to track ocean currents. Notably, the Friendly Floatees incident in 1992 involved 29,000 plastic toys falling into the Pacific Ocean, allowing researchers to study the pace and reach of ocean currents.

Flotsam, including natural items like pumice rafts from subsea volcanoes and discarded items like cigarette lighters, has also been used to map ocean currents. Researchers in Japan have even proposed using cigarette lighters for this purpose, as they often contain printed information about their consuming country or city, making their source traceable. By analyzing thousands of lighters collected across the North Pacific over seven years, researchers were able to map marine litter flows across Asia and the US, aiding in understanding the origins of plastic pollution on beaches.

Tracking the origins of washed-up debris can provide insights into invasive species’ potential spread across oceans. In 2011, the tsunami in Japan resulted in five million tonnes of debris being carried out to sea, some of which took more than a year to reach the western US and Canada. Among the debris were marine creatures typically found in Japan’s shallow waters, leading to concerns about their potential impact on North American biodiversity.

While the recent mystery sphere found in Japan remains unidentified, it is likely a mooring buoy rather than something more exotic. Nonetheless, speculation and media attention around these mysterious objects persist, capturing people’s imaginations with each new discovery washed ashore.