22 Dec 2015

A piddock shell (and King George V).

There have been a couple of days of gales, and the strandline was littered with shells including this half of a piddock:
The right hand side looks like a vanilla bivalve shell, the left is heavily distorted from the effort of grinding its way into shale to make a burrow. In many years of watching this beach I have never seen a live piddock; they obviously can't survive in an intertidal zone so well patrolled by gulls and oystercatchers. Their burrows show up in witchstones; pieces of shale with holes which were once piddock burrows which have been washed ashore. Local legend has it that if you nail one of these above your stable door it will ward off any witches that may try to steal your horse.
A piddock-bored witchstone, with Enteromorpha seaweed, a scattering of small barnacles, some encrusting red algae and a whelk.

I wondered if piddocks had any chemical help to bore into the rock but @RudkinDave said not, although other families of boring molluscs do secrete acids to help their digging. Having dug its burrow the piddock hunkers down, expends its syphon into the water and lives for around eight years. 

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