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 specific economic events that took place during the Great Depression have been studied thoroughly: a deflation in asset and commodity prices, dramatic drops in demand and credit, and disruption of trade, ultimately resulting in widespread unemployment and hence poverty.