Worms don't cause the skin condition known as ringworm. Rather, this superficial skin infection, also known as tinea, is caused by fungi called dermatophytes. Fungi are microscopic organisms that can live off the dead tissues of your skin, hair, and nails, much like a mushroom can grow on the bark of a tree.
Ringworm is characterized by a red ring of small blisters or a red ring of scaly skin that grows outward as the infection spreads. Though children are especially susceptible to catching ringworm, it can affect adults as well. Read more about ringworm.