A huge dock torn from a Japanese port by the 2011 tsunami has washed up 8,050km (5,000 miles) away on the US West Coast after crossing the Pacific.
The 165-tonne structure made of concrete, metal and tyres, and studded with starfish and barnacles, arrived on a beach south-west of Portland, Oregon.
It has tested negative for radiation, but scientists say a host of invasive marine species may have hitched a ride.
Police are guarding the dock while officials decide what to do with it.
This April, the US Coast Guard used cannon to sink a crew less Japanese ship that drifted to Alaska after the tsunami.
A month later, a Japanese owner of a Harley-Davidson motorbike swept away by the tsunami was amazed to find out that it had been washed up inside a container on a beach in Canada - about 6,400km away.
The long term effects of the Japanese tsunami are still being felt.
The huge devastation has caused millions of tons of debris to be carried over the Pacific ocean that are now turning up in the western US and Alaska shores.
Although the wreckage has been deemed to be non radioactive it has become a problem for coastguards who have to make safe large, heavy and unlit objects drifting of the the U.S coast.
the effects of the tsunami