A newly discovered collection of prehistoric markings on a Wharfedale moor has been dubbed Fraggle Rock.
Local antiquarians uncovered the strange-looking stone, covered with ancient cup and rings marks, during an exploration of Burley Moor.
It is one of a series of clusters of previously unrecorded carvings found by Oakworth-based Paul Bennett and fellow enthusiasts Paul Hornby and Michala Potts.
It earned its name due to the Muppet-like frowning face the carvings appear to make.
Mr Bennett has been fascinated by the hidden archaeological treasures on local moors since childhood, and documents his findings on The Northern Antiquarian website.
He said: “These carvings were found as a by-product of uncovering a previously undiscovered cairn circle, close to the Twelve Apostles stone circle.
“In assessing and exploring the new circle, it was noticed a small opening in the near horizon highlighted a rise in the landscape barely a mile away. I thought ‘we need to have a look at that site’.
“We came across a couple of previously unrecorded cup-marked stones, of simple design, right in line with the cairn circle. As we walked around, then headed back, a cluster of small stones were noticed on the slope.
“One had what looked like a single cup-marking near its edge, but the rest of the rock was completely covered in vegetation.
“Paul and Michala had, by now, already found several other previously unrecorded cup-marked stones close by, but as I rolled back the vegetation, cups-and-rings and carved lines seemed to be covering most of its surface.
“We called it the Fraggle Rock after noticing that, when you look from one end, the two main cup-and-rings are like two large eyes carved above a large, natural down-turning ‘mouth’ feature - similar to some of the creatures’ faces on the Muppets, or Fraggle Rock.
“The main design consists of at least three cup and rings, two partial cup and rings, 28 cups and several carved lines, along which some cup-markings are linked to others."
The group found another, faint cup-and-ring marking ten yards south of the spot and a “fascinating cup-and-lines stone, with at least four long carved ridges running like hair from the top of the stone into the earth”, 20 yards to the west.
The Fraggle Rock stone is just the latest in a line of artefacts that have been discovered by the group.
In 2010 Mr Bennett and friends unearthed an eight-cairn ancient burial site on Askwith Moor which, after checking with North Yorkshire County Council's archaeological consultant, they believe has never been recorded.