system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] How do the sand worms get enough nutrition/food in a such inhospitable desert to grow so large?

Does spice have something to do with it?
gpt
It takes a very long time and sandworms live for many thousands of years. They eat both large things and small things, filtering microorganisms from the sand and may even use the sand itself. This may be similar to the Blue Whale, which is the largest animal on Earth yet survives by eating some of the smallest (plankton). 

Additionally, Arrakis is inhospitable *because* of the sandworms. The planet was once temperate but the sandworm larvae sequestered water deep underground, creating the dry conditions that a mature sandworm requires.

Spice is produced by these larvae deep underground and is released when decomposition produces the right conditions (producing a pocket of gas) to blow it to the surface. This is then fed on by organisms closer to the surface which, in turn, can be fed on by the sandworms. Arrakis only appears inhospitable because we are mostly water and live on the surface.