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 Great Depression began by the complete collapse of the stock market on October 24th, 1929 when about 13 million shares of stock were sold. The damage was extended on Tuesday, October 29 when more than 16 million shares were sold making the day forever known as Black Tuesday.