Sew my true love to my side and down the road we'd go

I am incredibly charmed by this paper from Vannier et al.: "Collective behaviour in 480-million-year-old trilobite arthropods from Morocco" (Scientific Reports (2019) 9:14941). What the fossils in question appear to document is a mass migration of trilobites (Ampyx priscus) traveling in caravans across the seafloor in much the same manner as their contemporary relatives the spiny lobsters, who organize their own migrations in single-file, tip-to-tail chains, always maintaining antennae-contact to ensure that everyone moves in the right direction and no one gets lost, at least until everyone gets buried under a sudden wave of anoxic sediment, which seems to be what happened to this particular convoy of trilobites. The significance is that if animals were coordinating their behavior to act as groups in the Lower Ordovician, the capacity for it must have developed much earlier. The image of trundling columns of trilobites is also irresistible. I can thank the authors for introducing me to the phrase "spawning congregations," which feels distinctly Innsmouthian to me.