The July 8 story about “trilobite farming” states that “these trilobites would be the earliest creatures known to have forged a partnership with another species.” What about the fact that eukaryotes formed a partnership with other single-celled creatures that became mitochondria or chloroplasts? Now, if you mean that this was the first extracellular partnership, then maybe the trilobite was first.

Gregory V. Richardson
Anderson, Ind.