What item does Jerome (Vincent) place on the comb at his workstation?

In the context of the film "GATTACA," Jerome Vincent uses a hair on the comb at his workstation to emphasize the significance of genetic identity and the importance of one's DNA in the society depicted in the film. The use of hair is particularly poignant because it contains genetic information that can be analyzed and compared to determine a person's genetic background or potential.

This detail reflects the underlying themes of genetic destiny and personal identity central to the narrative. As the film portrays a world where genetic engineering dictates someone's place in society, the act of placing a hair on the comb serves as a visual reminder of the character's struggle against the societal norms that judge individuals based on their genetic makeup. This action ultimately underscores the concept of individuality versus genetic identity, a critical analysis point in the film.