We investigate the nature of the clumpy structures seen at high redshift. For this we use a 3D chemodynamical simulation including dark matter, stars and a multiphase interstellar medium as well as feedback processes from the stars. The infall of baryonic matter leads to the formation of a disk which later fragments and develops starforming sub-galactic clumps. Calculating U, B, V, K colors of the model including absorption by interstellar material we find similar morphology and colors as for multiple clump and chain galaxies in the HDF.