Galaxies can be very magnetic. This is observed via polarisation and Zeeman effect. Magnetism of this size can only come from electrical currents in structures of similar size. So this observations means that some of those electric currents might connect different galaxies.

In similar sense, Halton Arp already observed connections between galaxies and quasars.

This made him realize that something was wrong with the redshifts of quasars. He wrote about it and soon after that he was expelled from the astronomy community.