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Yours looks like it might be a Tiger Cowry, and from what I can find they're reef safe with caution. It might eat soft corals, leathers, sponges, anemones, and starfish and once it gets big enough it might move and/or damage corals because of it's size.
Juveniles eat algae/detrius and adults are more carnivorous, atleast according to that page I linked. Live Aquaria has similar info.