Just recently we were pottering happily along a pebbly beach on the island of Lismore, and some of the stones that we were picking up looked like this:
Just one pebble with a hole in it you could probably accept as a happy stroke of luck – but there were many more! Some had just one hole, beautifully drilled and smooth on the inside, just wide enough to put your little finger in; others were perforated with a network of tiny tunnels, so that if you held one up you could see a thousand pinpoints of light. But how do these holes occur? They are certainly not caused by the sea. The culprit is a mollusc, and it is called a piddock.
WHAT ON EARTH ARE PIDDOCKS?
Piddocks are bivalves, and their specially-adapted oval shells are edged with fine teeth which they use to excavate burrows…
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