
Nutmeg is the actual seed of the tree, roughly egg-shaped and about 20 to 30 mm long and 15 to 18 mm wide. Mace is the dried "lacy" reddish covering or aril of the seed. This is the only tropical fruit that is the source of two different spices. (Source: none other than Wikipedia).
When making the oatmeal muffins, I was surprised to find that I had a tin of mace in my cupboard, given that I can’t remember the last time I might have used it. Clearly, I don’t agree with the lifestyle gurus who suggest throwing out all unused herbs and spices yearly and restocking.
When I left home to live in my first apartment, I took my mother’s cache of spices with me. One bottle of cayenne pepper had a definite vintage look to it even then; I expect that it might have been purchased in about 1950. Honestly, I don’t think these things go bad; they may lose some potency but if that’s the case, you can just add more to the recipe. Didn’t the early Egyptians bury their pharaohs with a lot of spices to ‘tide them over’ into their next life? I'll bet that you could still bake a pretty tasty apple pie with some of that stuff.