Everyone suggesting to replace the paper wallet with a metal wallet are the missing the point. Yes, a piece of (the right) metal is sturdier than a piece of paper, but it is neither indestructible nor immune to loss or theft. You need redundancy in your back ups - not just for bitcoin wallets, but for everything. Two pieces of paper with the same information stored on them in separate geographical locations is exponentially more secure than a single piece of metal.

There is nothing wrong with using paper as a wallet or as a back up for you seed, and indeed, many of the metal back up solutions are grossly overpriced for what they are given that you can obtain a piece of stainless steel at your local hardware store for less than 10 bucks. The safety hinges on having multiple back ups, not one.

Aluminum is definitely not immune to fire, and will melt at temperatures well below those reached in an average house fire. Stainless steel provides the best trade off between cost and durability.