|Compare bilateral symmetry a type of structure of an organism or part of an organism in which a vertical cut through the axis in any of two or more planes produces two halves that are mirror images of each other|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
Symmetrical arrangement of parts of an organism around a single main axis, so that the organism can be divided into similar halves by any plane that contains the main axis. The body plans of echinoderms, ctenophores, cnidarians, and many sponges and sea anemones show radial symmetry. Compare bilateral symmetry.