What are those rocks with nails and blood in the Chaos Wastes?

I was wondering about the significance of the recurring items in the Wastes.
We have discs of Tzeentch (or items who look like them) and I was wondering about the floating rocks with blood flowing from them. Are they a Khorne thing?
What about the sharp things that resemble the tomb of gulmagak, the thing in the roof of the ritual in convocation and in that painting by Cathrinne, the one symbolizing Nurgle’s influence over Helmgart?
Is there a symilar thing for Slaanesh? I’ve only noticed banners with blades.

Why not join the Fatshark Discord https://discord.gg/K6gyMpu