Keeping it Eric's grandma-friendly, probably being eaten alive but paralyzed by magic/poison, which is a thing that's pretty easy to happen, even with low-level opponents. Ghouls, carrion crawlers, rot grubs, etc. etc.
Full-body petrification is pretty clean generally speaking. Partial petrification, now that's super-horrifying (c.f. ASoIaF and various other fantasy novels), straight-up body-horror stuff there.