Floating Rocks!

“Wot’s these little rocks then?”
“Pumice stone” came the reply from the Silverback.

“How did they get onto the beach?”
“We’ll, a volcano erupted somewhere in the Pacific Ocean and they were shot up into the sky. Because they’re full of air bubbles they are light enough to float. Then they drifted around out to sea for months until the wind and waves were right to wash them ashore on the dog beach” sez he.

I thought for a moment.

“Pull the other leg, it plays Jingle Bells” sez I.