What is it when an answer just comes to you, and you don't know why?

As many of you know, at the lake on Saturday afternoon Rick and I saw some birds neither of us had seen before. It was strange in that they flocked in a big tree like black birds, but from there a lot of them would jump in the water and start paddling around like a duck. We were talking about them, trying to figure out what they were, and out of the blue I said, “Cormorants.” I don’t even know anything about cormorants, except that they are a bird.

Turns out, they were cormorants. How did I come up with the right answer like that?