Curiosity recently stumbled upon a piece of plastic on the ground, something which researchers really weren't expecting.
Don't start thinking Martians have invented plastic or something like this - the piece is probably just debris from the shuttle or Curiosity itself. However, scientists are cautious and want to analyze it first before jumping to conclusions. To proceed thoroughly, the team is continuing the investigation for another day before deciding whether to resume processing of the sample in the scoop. Plans include imaging of surroundings with the Mastcam.
Who knows, as unlikely as it is, it might actually be a new mineral phase, one which could help us understand more about how the red planet was formed and evolved through geologic eras.