Scientists now know what an enzyme important in aging and cancer really looks like. A new study, published Wednesday in Nature, describes the structure of telomerase in more detail than has ever been done before.

Telomerase helps maintain chunks of DNA at the ends of our chromosomes called telomeres. Telomeres are like the caps at the tip of a high heel—over time, they get ground down until there’s nothing left. As a result, telomeres are often used as a shorthand for cellular aging—the shorter the telomeres, the older the cell (and the person to whom it belongs).