Morning Conversation

This morning Daniel drew something that looked like an amoeba with a stick . In eagerness he asked me to guess what it was. I didn't have the faintest idea of even where to begin guessing, so I asked for a clue. Giggling, he said, "It lives in the ocean...." I guessed a swordfish. A jellyfish with one tentacle. Laughing in anticipation he said, "Here's another clue, it's a little bit like a unicorn, but it's not a unicorn" Was he really talking about a narwhal? It seemed unlikely, but I guessed the narwhal, and he jumped in pleasure and said, "You're right! It's a narwhal! You're smart!" Where did he learn about narwhals?