Wild Collected snails

I wild collect snails for my tank and the kids found a couple along with some hermit crabs. Well one was HUGE, like bigger than a golf ball. Turns out it was a moon snail. Discovered they eat mostly shelled critters, but I'm wondering what may potentially be on the menu if clams and such are unavailable? The big one went back to the ocean but there's still a small one buried under the sand. Would it eat steamers?

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