The crystal habit of a mineral describes its visible external shape. It can apply to an individual crystal or an assembly of crystals. In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. Each crystal can be described by how well it is formed, ranging from euhedral, to subhedral, and anhedral. The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like. Recognizing numerous habits helps a mineralogist to identify a large number of minerals. Some habits are distinctive of certain minerals, although most minerals exhibit many differing habits. Crystal habit may mislead the inexperienced as a mineral's internal crystal system can be hidden or disguised.