Ancient BarkPick it up to discover it.
SilverPick it up to discover it.
Ymir FleshPick it up to discover it.
Freeze GlandPick it up to discover it.
ForgeDiscover and use at level 3 or higher.
Discovery is separate from having enough materials to craft. Check shelter, fire, placement, and station access in-game. This checklist cannot diagnose broken mods or save files. Each alternative recipe is listed separately.