Pendulum can be made from many things such as a crystal or a metal weight suspended on a chain, and used in divination and dowsing, particularly in remote or "map dowsing".
Historically, dowsing has been known for its ability to locate water, gold, oil and other minerals, and answering questions.
Across Europe it is sometimes used for medical diagnosis this practice is known as Radiesthesia (French - Radiethesie).