Galaxy formation simulations of the future of the core of A2744z7p9OD. (a) Gas density in a region similar to the proto-cluster A2744z7p9OD at a cosmological age of 689 million years. (b) A zoomed-in view of the core region in (a) corresponding to the region observed by JWST. The color map indicates the light distribution of oxygen ions. (b) to (d) show the evolution of the simulated object: the four galaxies gradually merge and evolve into a larger entity. Credit: T. Hashimoto et al.