Critterposting, Pistol Shrimp
Y'all have heard of pistol shrimp likely. They're a family of snapping shrimp called Alpheidae that snap and produce cavitation bubbles, which they use for hunting.
The collapse of the cavitation bubble creates a pressure wave that can kill small animals. They're some of the nosiest little bastards in the whole ocean, and account for something like 20% of all ocean noise as i recall.