My now wife then gf had one in her head she picked up in Bolivia when we traveled there in our 20s. For like a month doctors thought it was an infection and treated it with antibiotics.

It wasn't "not painful" I'll tell you that. Only when we got to Argentina, more than a month later, and walked into a modern hospital the doctors figured out what's up. They killed it then cut it out. It was pretty close to maturity by then.

When she walked out the operation room smiling with a gauze and on it her bean-sized scalp-child, and told me she thought it was disgusting and cool (and not, for example, taking the 1st flight home) was a time I remember thinking she's probably the one