Very cool! Could it have anything to do with salt content of the pooled water?
https://www.naturalworldfacts.com/post/the-secret-world-of-underwater-lakes
The Secret World of Underwater Lakes
Brine Pools appear to be dead-zones. Any organism to enter will suffer a toxic shock, But diverse biological communities form at the edges of these underwater lakes on the verge of life and death. Here, deep sea organisms from eels and hagfish to mussels relying on chemosynthetic bacteria producing ..
https://www.naturalworldfacts.com/post/the-secret-world-of-underwater-lakes
