According to a Live Science post, blue threads were found sticking to dental plaque in the mouths of two of the dead
after an examination of the bones of more than 100 sacrifice victims from the Maya Classic Period (A.D. 250 to 925) who were interred in Belize's Midnight Terror Cave.
Similar "Maya blue" pigment, according to archaeologist Amy Chan, has been discovered at other sites,
where it may have been applied ceremonially on the bodies of sacrificed victims.
Blue threads have been discovered in an agave-based alcoholic beverage discovered in tombs at Teotihuacan, a prehistoric metropolis in Mexico.
The rate at which plaque forms and hardens into dental calculus is unknown,
but Chan hypothesizes that the blue fibers discovered in the dental calculus may have been left behind by blue gags.
Chan and her colleagues came to the conclusion that more research is necessary to determine how the blue fibers were created.