pebble

With coastal erosion and the warming climate, he said the beach and nearby properties were at risk without the protective pebbles in place.

He said he had many moments over a two-week excavation where he thought he had discovered something, only for experts to tell him he had a knack for finding "shiny pebbles".

The post added: "The shell had been dug out of the pebbles by someone apparently, before someone else called 999 as they realised what it was."

The dramatic scene in which Mariko attempts to leave Osaka Castle with a group of advisors being held hostage inside sees her inching forward on the pebble road beneath her feet.

“And from there ... it’s like pebbles down a mountain.”