A sea smoothed Concretion - Concretions can form in sedimentary layers (river delta layers in this case) around bits of organic material or pebbles, which then become harder than the surrounding rock. They often erode out later as circular or rounded stones - water, waves and sand have finished the polishing job on this one. County Clare, Ireland. Cormacscoast.com walking tours #wildatlanticway #walkingtours #discoverireland #keepdiscovering #fossil #irishfossils #concretion #geology #pocketpebb