Danionella dracula

One of the evolutionary peculiarities of my favorite lab animal, the zebrafish, and of cypriniform fishes in general, is that they lack teeth. They lost them over 50 million years ago, and don't even form a dental lamina in development. So this photo of a cypriniform, Danionella dracula, gave me a bit of a start beyond just the nice fangs and the ghoulish name.
The story doesn't give much detail, but I'm going to have to look into this. Those are not true teeth, but spiny outgrowths of bone directly from the jaws.

Ghostshark (hydrolagus melanophasma)

A new ghostshark species has been identified off the coast of Southern California, and

it’s darker and weirder than any shark we know.

The purplish black ancient relative of the modern shark comes packed with a suite of odd features that give its taxonomical family the name chimaera, after the mythical beast made from the parts of many animals.

“It’s a big weird looking freaky thing,” said ichthyologist Doug Long of the California Academy of Sciences. “They have some shark characteristics and they have some that are very non-shark.”

Perhaps the most intriguing feature of the newly described species, Hydrolagus melanophasma, is a presumed sexual organ that extends from its forehead called a tentaculum.

“They have this club on the top of their head with spikes. People think it’s used for mating,” Long said. “It’s like a little mace with little spikes and hooks and it fits into their forehead. It’s jointed and it comes out. We’re not sure if it is used to stimulate the female or hold the female closer.”