A fifth reason is their involvement in a large number of human diseases, collectively referred to as neurocristopathies, an expanding research field that now benefits from decades of fundamental research on neural crest development. A fourth reason is the apparent propensity of some neural crest cells to persist as tissue-resident stem cells in many adult tissues. Neural crest cells not only contribute a wide array of specialized cell types (e.g., neurons, glia, melanocytes, neuroendocrine cells, craniofacial osteoblasts, and vascular smooth muscle cells), but can also indirectly affect tissue morphogenesis by influencing the behavior and/or function of adjacent non-neural crest cells. A third reason is the multipotency of these cells, which is so extensive that the neural crest is even considered a germ layer on its own, just like the ectoderm, mesoderm, and endoderm. A second is the unique ability of these cells to migrate over very long distances during a relatively short time window. One reason is the central role these vertebrate-specific cells played during evolution. There are several reasons why so many researchers remain fascinated by neural crest cells more than a century after their first description.