Cultured pearl is calcium carbonate and a fibrous protein called conchiolin. As the nacre builds up in layers of minute aragonite tablets, it fills the growing pearl sac and eventually forms a pearl. Natural pearls are formed by nature, more or less by chance. On the other hand, cultured pearls are human creations formed by inserting a tissue graft from a donor oyster, upon which a pearl sac forms, and the inner side precipitates calcium carbonate, in the form of nacre or "mother-of-pearl". The most popular and effective method for creating cultured pearls are made from the shells of freshwater river mussels
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