Cnidaria is a phylum within Kingdom Animalia which consists of hydras, jellies (or jellyfish), sea anemones, and corals. All cnidarians are radially symmetrical, and there are two main radially symmetrical body types.
The stock market crash, on black Tuesday (October 29, 1929) began the Great Depression.
Though the U.S. economy had gone into depression six months earlier, the Great Depression may be said to have begun with a catastrophic collapse of stock-market prices on the New York Stock Exchange in October 1929.