What is the treasure in sims 2 castaway?

Its on the 2nd island, on West Beach, behind a boulder. Inspect the boulder, and if you have all the pieces to the treaure map, your sim will push the boulder aside..and there is the treasure.

also you may want to remember the phrase, "If ye discover to much, ye may discover ye own doom." Although i don't know if you might die. I have looked everywhere in the the area, so i think it was a gag they put there.