Mom: "Do you know where butterflies come from?"
Tim: "Caterpillars. Caterpillars turn into butterflies."
Mom: "That's right!"
Tim: "Butterflies turn into raccoons."
Mom: [pauses for thought] "Oh, you mean cocoons. Caterpillars make cocoons."
Tim: [slowly and patiently] "No. Butterflies turn into raccoons!"
So there you have it. Another mystery of nature solved!