Pearl or parasite enters a bivalve mollusk and settles inside the shell. The mollusk, irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare. Typically, the build-up of a natural pearl consists of a brown central zone formed by columnar calcium carbonate (usually calcite, sometimes columnar aragonite) and a yellowish to white outer zone consisting of nacre (tabular aragonite). In a pearl cross-section
Pearl of Africa Rally its own African Rally Championship event in 1997. As Winston Churchill visited Uganda, he baptised the country as the ‘Pearl of Africa’, that's where this event receives its name from. Some remarkable drivers in the history of Uganda are Sospeter Munyegera, Shekhar Mehta, Satwant Singh, Charlie Lubega, Moses Lumala, Emmanuel Katto and Chipper Adams, amng others. Source: Motor Sport Uganda and African Rally Championship Pearl of Africa Rally Pearl of Africa Rally or Pearl of Africa Uganda Rally is one of the main motorsport events in Uganda. It is part of the National Rally Championship and the FIA African Rally