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
Consequences of the attack on Pearl Harbor into the war at a time when he had not yet acquired full control of continental Europe — on the very day of the Pearl Harbor attack, Hitler himself had issued his Nacht und Nebel decree, concerning the suppression of resistance activities within Nazi-occupied lands. Hitler, who had previously declared the Japanese "Honorary Aryans" claimed that "this is what happens when your allies are not Anglo-Saxons". However, he decided war with the United States was unavoidable, and the Pearl Harbor attack, the publication of Rainbow Five, and Roosevelt's post-Pearl Harbor address, which focused on European affairs as well as the