Polyp-like protrusions which are histologically hamartomas. These can occur throughout the gastrointestinal tract. Hamartomatous polyps are composed of the normal cellular elements of the gastrointestinal tract, but have a markedly distorted architecture. The phenotype is Human Phenotype Ontology identifier HP_0004390 (Hamartomatous polyposis). Also known as: Gastrointestinal hamartoma, Hamartomatous polyps.