18W07A spawning bug

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by the way, it was in multiple locations. I thought maybe they were coming from a glitched cave but there was no sign of one and they were spawning everywhere as if I was in a desert at night.

I believe its the kelp and seagrass making air space so mobs spawning thinks its a cave because of the level they are at and because there is no light in water. I realized because squid are dying in the seagrass and kelp so there must be air there.