The basic anatomical pattern (or body plan) of vertebrates has remained unchanged through billions of years of evolution. This conservation can be explained by the conservation of the body plan-establishing phase during embryogenesis. Meanwhile, it remains unclear which structures or cell types that constitute the body plan have been more deeply conserved. In this study, we aim to explore features or cells that have either changed or remained unchanged in the body plan, shedding light on both the ancient and novel structures that make up the body plan.