36 Steromphala cineraria with Polydora damage. Menai Strait, Wales. 2014. Left: breadth 14.7mm. Right: breadth 13.2mm.

36 Steromphala cineraria with Polydora damage.  Menai Strait, Wales. 2014. Left: breadth 14.7mm. Right: breadth 13.2mm.

1: channel cut by a commensal Polydora worm rubbing its acid secreting body across shell when extended from umbilicus (gelatinous tube removed).
2: As ‘1’ with worm (dead) extended from umbilicus.