Space fans on online discussion forums remarked that it might be quartz embedded in the rock. One optimistic commenter suggested it might be the pistils of a blooming flower, the New York Daily News reported.
A similar find in October 2012 had turned out to be a piece of plastic that had fallen from the rover itself.
"But the cluster appears to be part of the rock," Nasa spokesperson Guy Webster told the Daily News in an email.
"I would guess that the 'flower' was someone's descriptive term for its appearance, not meant as an interpretation that flowers exist on Mars," he wrote.