I like looking commonplace things up on Wikipedia. Sometimes I'm surprised by the gap between what I think I know and what I don't know. Sometimes, I'm just surprised. For instance, take this excerpt from the Wikipedia entry about "watermelon".

The watermelon fruit, loosely considered a type of melon (although not in the genus Cucumis), has a smooth exterior rind (green and yellow) and a juicy, sweet, usually pink, red, or yellow, but sometimes orange, interior flesh. The flesh consists of highly developed placental tissue within the fruit.

I may never eat watermelon again.