The phrase "mere fragments" refers to small, incomplete pieces or parts of something. It means that only a small amount or portion of something is present or being referred to. Full definition
He eventually was able to identify the drawings even with mere fragments. (discovermagazine.com)
Starting with mere fragments of DNA, the scientists can reconstruct entire genomes of these animals to better understand how species respond to rapid changes in the environment. (sciencemag.org)
As mere fragments of genes, ESTs by themselves generally have no intrinsic function in an organism. (sciencemag.org)