Blooper

Fun story - as a kid my backyard in-ground pool would occasionally get these grapefruit sized ant rafts. No idea why or how they would do it, but somehow they’d find themselves floating around in there. And if you don’t look too closely it just looks like a dead leaf that landed in the pool.

Dove in one hot summer day. Came up for air. Facefull of ants. Never again.

Out of curiosity and slight discomfort, what is that black object in the top left corner?