Does Fish Tank Gravel Actually Serve Any Purpose?

Have you ever thought that fish tank gravel serves no purpose at all ? If anything, at times, it is more of a hindrance to your viewing pleasure and makes cleaning the tank much harder. Is it's purpose purely to create a landscape that humans can identify with and is no use to the acquatic inhabitants ? Interestingly enough, fish tank gravel actually does serve a purpose: it covers the bottom of the tank, which is a significant part of the nitrogen cycle in your mini ecosystem.