Toothpaste curiosities

So picture this scene. Ryder and I are walking upstairs and I am carrying some toothpaste that we purchased earlier today. And Ryder turns to me and says, "Mommy, what is toothpaste made out of?" Huh??? Why would a two year old think to ask this question? Anyone who can answer this question, or even tell me the first ingredient, without looking it up can have a prize. I totally didn't know, which made me happy that I had the toothpaste in my hand and could look it up. Just for everyone's knowledge, the main ingredient is silica, which hasn't been the guess of anyone I asked so far. Thanks for helping make me smarter, kid.