Yes, there are many species that are normally hermaphroditic, and it can happen as a sort of genetic "oops" in lots of species that normally aren't hermaphroditic as well.
Yes, earthworms are coelomates because they have the "tube within a tube" body plan that characterises coelomates. More specifically, coelomates have a body cavity that is completely lined with cells...
Usually the for basic elements are water, earth, air and fire, but many other elements have been added such as light, dark, moon, sun and ice. These elements are usually used in the Japanese/Chinese...