Mummies

@kretorrbwly  Is this sim already some kind of occult, or pregnant?  If so, that's why she didn't transform.  Try again with a human sim that isn't pregnant.

I haven't heard that time travel can produce mummies.  What I've read is that there's a way to cure the mummy's curse through time travel, but you clearly aren't interested in that outcome.

If you have Supernatural installed, probably the easiest way to create a mummy is to make or buy the related elixir.  Otherwise, you can collect the five canopic jars and put them in the cursed sarcophagus, and a mummy should emerge.  These need to be the special relics, e.g. Canopic Jar of the Cat, not the standard ones that sit in a stack of normal relics like bowls and vases.