Cracking shells

Walked from site into Caernarfon, lovely dry day. Coffee, wander round, lunch and walk along the shore line to the golf course before returning to the camper. It was actually quite warm at times.
Got lots of seabirds and waders and kept hearing a tap on the stone beach and noticed the gulls were dropping things and then landing. I have never seen them do this before, don’t know if they were cracking the shells but they were certainly eating whatever they had dropped.