Michael Stevenson from Canberra, Australia, took this photograph in Mongolia in 1995 on the road between Ulan Bator and Terelj.

“Not only did it look like a turtle, complete with carapace and flippers, from the road but it looked like a turtle from all sides,” he writes. “As you can see, it is on a slight rise, well above the surrounding countryside. To give some sense of scale, I am the person in the photograph and I stand 194cm (6ft 5in) tall. Terelj is Mongolia’s main tourist area and I cannot understand why no mention of this bizarre rock formation has ever appeared in a travel guide.”