... (finish the sentence and give a reason for your answer). This thread is inspired by the gnats attacking me in the yard today. Grrrrr. Hate it when those buggers get stuck in my eyes.
Water.
It self ionizes into hydrogen hydroxide, expands when it freezes thus making it float and is a chemical fairly close to a very universal solvent as far as what we have found goes (alchemists 'be hunting), but it is naturally occuring and doesn't destroy our bodies despite us containing a fair bit of it, relatively speaking to volume. And don't get me started in solid-liquid-gas forms!
Its crazy stuff. And its nice to drink. Absolutely bonkers.