What's the name of the horned aquatic mammal, possibly mythological?

Question

There's an aquatic horned mammal, I don't remember if it's mythological or not, to be honest. I can't seem to remember the name, nor are my web engine searches bringing up any results. I want to say it starts with a "t".. but I could be WAY off. Any help would be appreciated! :)

Answer 1

yes there is the narwhal. it is a real type of whale. the horn is actually a tooth.

or the only mythical creature i can think of is the capricorn, where in some artwork it is depicted as a goat's upper body with a fish tail.  

Answer 2

Narwhale.

Answer 3

Narwhal maybe.  

Answer 4

Narwhal is the name.  It is a real mammal not mythological.  

Answer 5

Monodon Monoceros, the Narwhal, although the "horn" is actually an elongated incisor tooth.