Water does not exist. The two main liquids are lava, and some kind of "life essence" (let's call it mana).
One random day, a rock solidified with the ability to produce mana through photosynthesis, and life appeared (only mineral lifeforms, nothing organic). Every living thing pretty much looks like a rock patchwork, glued and animated by mana.
Life evolved, humanoids appear, and reach an age where they are able to produce, extract, and use mana as energy through industrialization.
However, since nothing is organic, there's no wool or anything to produce fabric.
What would be an easy, cheap way to produce a fabric-like material ?
I'm fine with magic, but it needs to be plausible.