Howdy, I know this may be a weird question, but I was wondering if gelatinous cubes were lipid based, protein based, carbohydrate based or something I haven't thought of. I'm planning on making my players fight a few, but the storyline is going to be different depending on what the cubes are based on. 

Thanks!

Gelatinous cubes are acid-based creatures held in a structured matrix of gelatin, which is protein based. 

I think the closest we get RAW is: According to the Demonomicon of Iggwilv and other sources, oozes are scattered fragments or offspring of the demon lord Juiblex.

I don’t believe there’s been much research into demon physiology (stupid congress and their out of whack funding priorities). So it’s difficult to say what they are made of beyond demons and probably magic. I’d say just pick something and stick with it.

Quote from SpaceAce123 >>

Howdy, I know this may be a weird question, but I was wondering if gelatinous cubes were lipid based, protein based, carbohydrate based or something I haven't thought of. I'm planning on making my players fight a few, but the storyline is going to be different depending on what the cubes are based on. 

Thanks!

 They're magic based, but by default I would assume 'gelatinous' is literal, and gelatins are proteins.

I just figure they are some kind of land based jellyfish.  You get stunned, enveloped and digested.

Quote from SpaceAce123 >>

Howdy, I know this may be a weird question, but I was wondering if gelatinous cubes were lipid based, protein based, carbohydrate based or something I haven't thought of. I'm planning on making my players fight a few, but the storyline is going to be different depending on what the cubes are based on. 

Thanks!

 Perhaps different parts of the world/cave systems have them based on different assumptions - as you've listed above.

So what works on one type won't necessarily work on another type.

:-)