"The third dredge-up brings helium, carbon, and the s-process products to the surface," (emphasis added)
In the early universe, stars had so little in the way of "seeds" for the s-process to act on that the few seeds that were there absorbed large numbers of neutrons, eventually producing weird stars highly enriched in lead (the end point of the s-process). These stars have been detected from lead (and bismuth) in their spectra.
"The third dredge-up brings helium, carbon, and the s-process products to the surface," (emphasis added)
In the early universe, stars had so little in the way of "seeds" for the s-process to act on that the few seeds that were there absorbed large numbers of neutrons, eventually producing weird stars highly enriched in lead (the end point of the s-process). These stars have been detected from lead (and bismuth) in their spectra.
https://en.wikipedia.org/wiki/Lead_star