Ptolemy could not explain * Retrograde motion of the planets* with out epicycles and deferents.
El huevo amniótico de reptiles y aves está rodeado por una cáscara externa resistente que protege al huevo de los depredadores, patógenos, daños y secado.
Most terrestrial animals crawl. Snails and slugs crawl on a specialized foot. Newts, salamanders and lizards crawl too. Frogs and toads crawls when they are not hopping and so do insects. Flies, moths and bees crawls when not in flight. Some animals crawls at some stages of life but not others - for example baby humans crawl as do caterpillars before they turn into butterflies!
Hope this helps :)
That my good friend would be B. tissue. Or a bunch of cells stuck together to build muscles in your body.