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
The Pearl of Death and kills him, after which Holmes kills the Creeper, before the police finally arrive. Holmes smashes the final bust and recovers the pearl "with the blood of five more victims on it". Universal Studios attempted to capitalise on Rondo Hatton's effective portrayal of the Hoxton Creeper, casting him in two more (unrelated) films as "the Creeper": "House of Horrors" (filmed in 1945, but not released until 1946, after Hatton's death) and "The Brute Man" (1946, also released posthumously). The Pearl of Death The Pearl of Death is a 1944 Sherlock Holmes film starring Basil Rathbone as Holmes and Nigel Bruce