Ok, so it has maybe one root (on the right). Would you keep it out of soil with this? Should it sit on some pumice or sand or just a flat surface? Is inside ok? What would cause it to have no roots?

Hello! I have had this cactus (gymnocalycium horstii?) nearly 30 years and it made pups about 5 years ago. Since then, it has continued to shrivel and the color has been less vibrant with the brown patches. Does anyone have advice?