The hard exoskeletons of trilobites made them as good as literate.
They wrote their stories not on paper but on the stone of millions of fossils. These volumes cover my body in every former ocean where they swam. Like miniature libraries, with many different stories. The winglike heads of the earliest forms, the trident horns of others. All variations on the same theme: a rounded shell, segmented spine, and vertical symmetry. They would live 300 million years, a good life. But still, I miss them. They left only their records but no true descendants.