When in normal motion, the only soft parts that protrude from the shell are the cephalic tentacles 1 and the translucent, white pallial tentacles around the rim of the aperture 2 . Occasionally, the tip of the ctenidium protrudes a little at the anterior right.
Touch sensitivity of the cephalic tentacles and pallial tentacles, plus that of the outer lips, is probably the main means of warning of attack.
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig