Intramural fibroids: Some fibroids develop within the muscular layer of the uterus, becoming part of the uterine wall and possibly changing its structure and overall size. Submucosal fibroids: These fibroids form just beneath the uterine lining, pressing into the inner cavity of the uterus. Pedunculated fibroids: These are the rarest form of fibroids, growing on a thin stalk connected to the uterus. Their shape often resembles a mushroom, with a narrow stem supporting a broader top.