Alright, because I knew this one would be too easy, I intentionally made the picture blurry so it would be a little harder. (As far as you know.)
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Any idea what that green coral is? It's soft and appears to be attached by a "stem" of sorts, as the whole round top part sways in the current.

Any idea what that green coral is? It's soft and appears to be attached by a "stem" of sorts, as the whole round top part sways in the current.