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That looks like fossilised coral (possibly a sponge?), the outside is smooth because it's been worn down by the erosion of the sea. There is quite a lot of fossilised corral on the north Wales coa...
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That looks like fossilised coral (possibly a sponge?), the outside is smooth because it's been worn down by the erosion of the sea. There is quite a lot of fossilised corral on the north Wales coa...