Elemental or elementary?
Elemental: adjective - being an element; specifically - existing in the form of an uncombined chemical element; the basic or essential constituent of something; fundamental, simple, uncomplicated; dealing with the rudiments of something; of, relating to, or resembling a great force of nature.
Elementary: adjective - dealing with the simplest elements or principles of something; relating to an elementary school.
So, something elemental is essential or integral to nature, whereas something elementary is fundamental.
‘The raging tempest that cast great waves on the shore, tearing up the coastal trees and upending the fishing boats, was elemental.’
‘I don’t see how you can pretend to be a writer, my friend, when you fail to understand the most elementary rules of grammar.’