I am looking for the real names of these creatures. Their name sounds something like "axel waddle"? Any ideas?

They are these creatures that live in water. My chemistry teacher had a bunch of them in his room at my school this year and claimed they were called (this is a total guess on spelling) axel waddles but when i google this and other possible spellings i get nothing. Does anyone know what they are called? It sounds weird but they actually look JUST like miniature versions of the dragon, Toothless, from How To Train Your Dragon. http://images2.fanpop.com/image/photos/11000000/Toothless-Grin-night-fury-11062607-689-520.jpg