That was a joke. Let me tell you the reason why it is funny...
What do an eagle and a mole have in common?
What do an eagle and a mole have in common? They both live underground, except for the eagle.
This joke is absurd. The punchline of the joke is not an answer to the question at all, though it claims to be. The humor of the joke lies in the fact that eagles do not live underground, and for a moment the joke seems to claim that they do.