One of the ingredients of the sacred composition which gave a sweet smell when burned (cf. Sir 24:15, where apparently the same substance is referred to as onyx). Onycha was obtained from the claw-like [hence the name from Gr. onyx 'nail'] operculum of some mollusc of the genus strombus. A similar product is still used in Upper Egypt for fumigations.
E. W. G. Masterman.