User blog comment:Echo 1/Elements You Should Not Give Your Characters/@comment-1221909-20130512075034/@comment-24510871-20130513141842

I've always found it quite hard to distinguish between the two. Being an avid fan of the Avatar television series only makes the problem worse, as earth and stone are one and the same, as is iron to some extent.

I try to think of earth in BIONICLE terms as the ground, whilst I believe stone to be the the actual minerals many stones are composed of. Might not be correct, but it helps keep the two ideas separate. Although I'm quite sure there was a quote somewhere of someone being able to tell them apart; I can't remember it, though.