The time it would have taken for the limestone to build up around what appears to be a washing detergent bottle – the average growth rate is 0.13 mm a year – suggests it has been there for decades. The limestone has even grown through the handle.
He told the Independent: “We have a few remote coves near us and try to check them out as often as possible.
“The plastic bottle was wedged into a limestone cave. It must have been there decades.
“The limestone built up around it and it’s now part of the structure.
“It shows the strength and durability of plastic and how nature is being forced to literally absorb it.”
Rob says Beach Guardian volunteers normally clear out the plastic they find, but he wants to consult with a geologist before he attempts to remove the bottle.
“We are not sure what to do with it,” he said. “It could break up into smaller particles or damage the limestone. We would welcome feedback from a geological expert.”
Studies estimate there are now 15–51 trillion pieces of plastic in the world’s oceans and is found everywhere from the equator to the poles, from Arctic ice sheets and the sea floor.
A post on the Beach Guardian’s Facebook page reads: “This weekend we checked out this cove for marine plastics but decided to take some stronger lighting into the cave for a closer look.
“And we made this shocking discovery – a plastic bottle now encased in the limestone! These formations are made through deposition of calcium carbonate and other minerals, which is precipitated from mineralized water solutions.”
Beach Guardian organises community beach cleans and conducts educational workshops with schools and other groups.