Someone has: https://en.wikipedia.org/wiki/Self-interacting_dark_matter https://en.wikipedia.org/wiki/Self-interacting_dark_matter They even think about dark c

Someone has: https://en.wikipedia.org/wiki/Self-interacting_dark_matter https://en.wikipedia.org/wiki/Self-interacting_dark_matter They even think about dark chemistry: https://iopscience.iop.org/article/10.3847/1538-4357/ac75ef https://iopscience.iop.org/article/10.3847/1538-4357/ac75ef Didn't have much support last time I checked.