Cactus identification (Mammillaria?)
Hello! Today I found a very nice cactus at the grocery store for very cheap, so of course I could not resist adding it to my collection. However, none of the cacti sold there are labeled and I have no idea what it is, other than I'm pretty sure it's some type of Mammillaria. It's about the size of a softball. I was hoping someone here might have an idea. I can take more photos if needed.
Also, I don't think I've posted here before. Hi! I'm new to collecting cacti, with a tiny but growing collection of about a dozen, but I have been bit by the bug hard, lol. Hopefully I'll be around a bit.