I got this cactus as a door prize at a faculty meeting a couple of years ago. It had fake flowers glued to it (way to go Wal-Mart!). I knocked it over and the fake flowers exploded so we pulled them off.
When we moved in to this house at the end of May, we repotted the cactus and since then it has grown pretty big. We were going to repot it again this week when we noticed these little nodes on the top. This morning, this is what I went out to: