Sentence:  The bivalve Posidonia permica frequently occurs in large concentrations on slabs of the shale in which there are also concentrations of cephaloped prehensile <WSD>armhooks</WSD> representing no doubt distorted natural assemblages from single individuals. 
Meaning of the word marked with <WSD> tags:  A hook-like projection on the arm of a cephalopod, such as on the armhook squid (Gonatus fabricii).