Pipe Rock

I'm no geologist, but I think this is Pipe Rock. Fossilised worm casts in quartzite sandstone. They are called Skolithos, vertical burrows. 
After many hours of clambering up rocks, I only saw them on the moonscape summit of Ruadh-stac Beag, a remote corbett in Torridon, an area famous for its sandstone.
Extra blip - hard to resist a summit photograph.