Sometimes we don't know what's weirder: nature's strange creations or the ridiculous names we humans give them. That is certainly the case with the Sarcastic Fringehead (Neoclinus blanchardi).
If you happen to spy one skulking away in whatever shell, rocky crevice or piece of rubbish they can find, they're typically seen as a dull brown boggle-eyed sockpuppet of a fish. It has also been called "spectacularly ugly" in scientific literature.
But if you take a closer look, or just keep watching for a while, these notoriously grumpy critters may just reveal a few surprises.
Sarcastic fringeheads live in the pacific waters, off the coast of North America - from San Francisco, USA to Baja California in Mexico. They are ambush predators, so they like to stake out a hide-y hole that offers them both protection and a great vantage point from where to pounce on prey.
Once they've reverse parked into their chosen nook, they'll aggressively charge at anything that comes too near - including divers. And rumour has it, they don't like to let go.
When rival males get too close to each other they unfurl shockingly large and colourful mouths and make gaping threats at one another, like yupping muppets.
If one of the males does not back down, this will escalate into a full-scale kissy battle - with the two rivals pushing mouth to mouth against each other in order to establish who's the biggest.
You can see them in action below.
Marine biologist Watcharapong Hongjamrassilp's thesis research suggests that they use the colourfulness of their mouths to communicate with each other. They don't look like they've got many nice things to say:
Isn't he just frightful? He certainly thinks he is.
But shhhh, don't tell them that.