The name of the super continent is Pangaea
Echinoderms, they are among the most common invertebrate animals in the marine environment of virtually any part of the world, among them we can find species such as sea cucumber , salmon and cod fish, they have chamois cloth like outer layer, then we have the Crinoids, another example of marine species with feather, popularly they are called sea lilies and feathery stars, they have a solid calcite skeleton; they were so abundant in the paleozoic seas that their remains formed large limestone thicknesses.
Mass number = protons + neutrons
If you have the # of protons and the mass #, subtract the number of protons from the mass number to get the number of neutrons.
If you have the number of neutrons and the mass number, subtract the number of neutrons from the mass number to get the number of protons.
