Related Clues:

• Change into bone, become rigid
• Turn to bone with age
• Change into bone, or become unprogressive
• Become hard and bony with age
• Cover lavishly, as with gems
• It's hard to make it like this
• That's just to make it hard
• If so, Y's able to get hard like this
• Put hard surface on counters, with nothing going wrong
• Harden when state beginning to freeze -- outside icy winds
• Turn to fossil (if fifty were unknown)
• Loss if your houses become inflexible
• You may get it from boss if you become inflexible
• Become rigid as bone
• Cover with a hard layer