what type of symmetry do sand dollars have
Sand dollar The bodies of adult sand dollars, like those of other echinoids, display radial symmetry. The petal-like pattern in sand dollars consists of five paired rows of pores. The pores are perforations in the endoskeleton through which podia for gas exchange project from the body. The mouth of the sand dollar is located on the bottom of its body at the center of the petal-like pattern. Unlike other urchins, the bodies of sand dollars also display secondary front-to-back bilateral symmetry. The anus of sand dollars is located at the back rather than at the top as in most urchins, with many more bilateral features appearing in some species. These result from the adaptation of sand dollars, in the course of their evolution, from creatures that originally lived their lives on top of the seabed (epibenthos) to creatures that burrow beneath it (endobenthos).
Gold standard This was meant to be a temporary measure, with the gold price of the dollar and the official rate of exchanges remaining constant. Revaluing currencies was the main purpose of this plan. No official revaluation or redemption occurred. The dollar subsequently floated. In December 1971, the "Smithsonian Agreement" was reached. In this agreement, the dollar was devalued from $35 per troy ounce of gold to $38. Other countries' currencies appreciated. However, gold convertibility did not resume. In October 1973, the price was raised to $42.22. Once again, the devaluation was insufficient. Within two weeks of the second devaluation the dollar was left to float. The $42.22 par value was made official in September 1973, long after it had been abandoned in practice. In October 1976, the government officially changed the definition of the dollar; references to gold were removed from statutes. From this point, the international monetary system was made of pure fiat money.