What sharp jagged mountain top.?

A sharp, jagged mountain top is often referred to as a "pinnacle" or "spike." These formations are typically created through geological processes such as erosion and glaciation, which wear away softer rock layers, leaving behind harder, more resistant peaks. Such rugged summits can be challenging to climb and are often sought after by experienced mountaineers for their dramatic landscapes and technical routes. Examples include the Matterhorn in the Alps and the Cathedral Spires in the Black Hills of South Dakota.