During the Jewish holiday Rosh Hashanah, celebrants blow into a shofar, an animal horn hollowed out into a musical instrument. The horn must come from an animal that chews cud and has cloven or split hooves such as a cow, sheep, or goat. Cow horns are frowned upon as they are considered reminders of the “Golden Calf” worshipped by Biblical idolaters that Moses found upon his return from Mount Sinai.