Sargassum Fish

Arthur and Theo like to bring large clumps of sargassum that floats into the bay onto the boat, investigating it for creatures; they were thrilled to discover this Sargassumfish. It was extremely well camouflaged, with feathery, plant-like growths all over its body that perfectly mimic the sargassum it hides in.

Typically grow to 8 inches in length. It is a type of frogfish, usually found in shallow tropical waters. As well as growths that mimic the sargassum it lives in, the Sargassumfish can rapidly change shade to better camouflage. Despite appearances, according to Wiki, it is a “voracious ambush predator that is also a cannibal”, searching for prey amongst the sargassum weed and using a projection on its head like a lure to attract small fish, shrimp and other invertebrates.

https://en.m.wikipedia.org/wiki/Sargassum_fish