At the eastern end of Geodha Smoo in the Durness Group limestones, is a curious limestone breccia, colloquially known as 'leopard rock'. The origin of the breccia is obscure; possibly due to bioturbation (burrowing) or a thrombolite (bacterial mounds/concretions) - although to me it doesn't particularly look like these.

Possibly the angularity of the clasts points towards a diagenetic origin, i.e. when the lime-rich muds were undergoing burial and mineralisation to form the hard rock we see today.