This is a movie that depicts somite formation in a live knypek; trilobite double mutant embryo. This is a dorsal view with anterior towards the top and time points were 15 minutes apart. Somites in knypek; trilobite embryos are composed of only two cells in the anterior posterior dimension. In addition, presumptive somite cells do not converge towards the notochord-somite boundary as somites form. Thus, neither compaction nor internal mesenchymal cells are necessary for somite formation. Video made available through Mark Cooper and Zebrafish - The Living Laboratory.