Onycha

Onycha (shecheleth in Hebrew; onyx in the Septuagint, though likely a different substance) was one of the four aromatic ingredients in the sacred incense burned before the LORD in the tabernacle (Exodus 30:34). The three other ingredients were stacte, galbanum, and pure frankincense. Onycha is generally identified with the operculum — the horny, claw-like covering of a sea snail (Strombus or Murex) from the Red Sea, which when burned produces a musky, animal-like fragrance. The burning of this compound incense was reserved exclusively for sacred use; its formula was not to be replicated (Exodus 30:37).