The Hebrew shecheleth of Exodus 30:34 is rendered onycha, fingernail, in the Septuagint. The leading identification is the operculum of a marine gastropod, which fits the sense, a nail-like hard plate, and the ancient aromatics trade. Benzoin, labdanum and rockrose are proposed plant alternatives but fit neither the sense nor the trade as well. A non-kosher animal product in the sacred incense is a live halakhic difficulty, which is the main reason the operculum identification is resisted by some commentators rather than for philological reasons. No reconstruction of the ketoret can be made without settling this, and it has not been settled.
What would resolve this A residue analysis of an incense deposit from a securely dated Second Temple period altar or vessel, compared chemically against operculum keratin and against the candidate plant resins, would settle which substance was actually burned.
OpenArchaeochemistry, biblical studiesMircea Eliade (ed.); Lindsay Jones (ed., 2nd ed.), Encyclopedia of Religion