You don't need to be afraid of this crocodile

Evolved to just eat fish, it poses minimal threat to humans with its extremely long, thin snout.

https://en.wikipedia.org/wiki/Gharial

Eels are kind of like Aliens. You know, from the movie Alien?

http://en.wikipedia.org/wiki/Moray_eel

They have a second set of jaws inside their mouth that they use to drag food in once bitten, since they can't swallow like many other animals using suction.

From weapon of war to weapon against cancer

Mustard gas, infamous for its role as a chemical weapon in WW1, was used to develop the first chemotherapy drug.

https://en.wikipedia.org/wiki/Sulfur_mustard