Mummy

The mummy is a new Life State introduced in The Sims 3 World Adventures. Normally, mummies are NPCs but sleeping in a cursed sarcophagus can turn a Sim into one.

Al Simhara
In Al Simhara, their home nation, NPC mummy will normally be inside their sarcophagus resting. However, upon detecting a Sim disturbing their eternal sleep, they will rise from their sarcophagus (you can sleep in a "cursed sarcoughagus of the kings" but you have to do it sevreal times to become a mummy, the blessed sarcoughagus of the kings can turn you back the same way.) and pick a fight with the Sim that is treasure hunting. If the Sim loses the match, he becomes cursed. The Sim must plead with the sphinx and acquire a special statue or the Sim will pass away within 2 weeks.

Biology
Mummies are covered in old, flammable rags. Thus if they catch fire, instead of the usual hour a Sim has before he turns into ashes, a mummy will die instantly. Also, mummies are very slow, so a Sim can outrun a mummy if he can flee the ruin he is in. However, being a mummy has it's perks as they are very strong in comparison to normal Sims, so Sims are normally outmatched by mummies unless they have a high Martial Arts skill level. A mummy can outlive a normal Sim by quite a few days. Also, their energy and bladder needs never decay.

Reverse
To reverse the life state and become a normal sim again, simply sleep in the blessed sarcophagus of the kings for a day or so, when you emerge you will no longer be a mummy. tested and proven.

Trivia
There is a mummy in the Sims 2 DS and GBA. He is called Horus Menhoset IX and lives in the desert, inside his Ziggurat.