A hexagonal bipyramid (shape that like a compass needle), usually green, which has become synonymous with Maxis' The Sims game series.
Often found floating over people's heads; may imply that the person is being controlled by another, literally or metaphorically.

For generic weights on strings, use plumb bob.

Official art and trivia: https://www.thesimswiki.com/wiki/Plumbob#Variations_of_the_Plumbob