scRNA-Seq has provided considerable insight into the development of embryos and organisms, including the worm Caenorhabditis elegans,[39] and the regenerative planarian Schmidtea mediterranea.[40][41] The first vertebrate animals to be mapped in this way were Zebrafish[42][43] and Xenopus laevis.[44] In each case multiple stages of the embryo were studied, allowing the entire process of development to be mapped on a cell-by-cell basis.[7] Science recognized these advances as the 2018 Breakthrough of the Year.[45]