Fibroids can grow in different parts of the uterus:

Under the outer surface of the uterus (subserosal fibroids)

In the wall of the uterus (intramural fibroid)

Under the lining of the uterus (submucosal fibroid)

Some fibroids grow on a stalk and can protrude into the abdomen or the uterine cavity. They are called pedunculated fibroids.