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.
The stock market crash of 1929, usually cited as the beginning of the Great Depression, was preceded by the Roaring '20s, a period when the American public discovered the stock market and dove in head first. The crash wiped out many people's investments and the public was understandably shaken.