It gets very cold in Scotland in December. Cold enough for ice pancakes! These strange discs of ice were seen on the River Dee at Lummels Pool in Aberdeenshire.
River Dee Team biologist Jamie Urquhart said it was thought foam floating about on the water started to freeze and bump together, forming the discs.
The phenomenon can be found in rivers and in the open sea.
Mr Urquhart, who found and photographed the "pancakes", said: "What we think happened is this - foam floating about on the water started to freeze, probably at night.
"Bits of frozen foam got pushed around in the eddy, and in the ensuing collisions became roughly circular."
There is more to the story of how the discs got their peculiar shape over several days. We could observe the process to make sure, but who wants to stay up all night outside when it’s cold enough for running water to freeze? See more pictures at BBC News.
(Image credit: Jamie Urquhart/River Dee Trust)