The six-wheel spacecraft captured an image of the puzzling object Monday after scooping up Martian sand and dust over the weekend.
In a statement Tuesday, the space agency says the plastic bit that fell off the rover is "benign."
While plans are continuing to positively identify it, NASA says it is not "Martian material." Curiosity will continue taking pictures of its surroundings as the project team decides the next move.
Curiosity landed in an ancient crater in August on a two-year mission to determine whether the environment was ever favorable for microbial life.
It started driving toward its first science destination after a month checking out its instruments.
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