N. lapillus bores neat hole through shell by alternating rasping by radula with application by accessory boring organ of enzymes and acid that soften conchiolin and lime in prey’s shell.
Top insert: completed bore hole showing nutritious viscera of P. vulgata at base. Radular rasp-marks running obliquely down sides of hole result from angle of radula being constantly changed to give smooth round hole; show that no rotary action involved.
Lower insert: completed bore hole after body of P. vulgata removed from shell.
Red arrow: hole positioned above pedal retractor scar where shell thin and viscera within reach of radula (see image 40dNl 40d Nucella lapillus bore-hole viewed from interior of Patella vulgata (33mm long). Lleyn, North Wales. September 2015. for interior view).

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