Gallery: genuinely spacetime

Groups whose symmetry entangles space with time: no Galilean change of frame — pan, re-basing of the spatial lattice, change of time origin or unit — makes them a static wallpaper with an independent clock. (One of them, the time glide, is a product after the unphysical relabeling of a space axis as time; see its caption.) Each animation is exactly invariant under the operations listed. Downloadable GIFs below each demo.