The black sea nettle (Chrysaora achlyos), sometimes informally known as the Black jellyfish due to its dark coloration, is a species of jellyfish that can be found in the waters of the Pacific Ocean. It is a giant jellyfish, with its bell measuring up to 1m in size, and its oral arms extending up to 6m in length. Despite its size, the Black sea nettle was only recognized and scientifically described as a separate species in 1997
Photo by Hugh on Flickr
No, I’m pretty sure those are corehound poops.