Some much needed historical context:
This sestina is about Mary Anning, one of the pioneering figures in early paleontology. During her life she was largely uncredited for her work and ended up having to sell the majority of her finds to museums and private collectors. The nursery rhyme "She Sells Seashells" is actually about her, which is how the public at large remembers her. The poem is predicated on the disconnect between being remembered as an anonymous nursery rhyme when the real story is much more compelling.