In the 2017 movie Justice League, Steppenwolf is looking for the Motherboxes that are located on Earth for Darkseid.
A few times, when looking at a Motherbox, Steppenwolf refers to some "mother".
Who is that mother?
I always assumed that, since the boxes are powerful artifacts, the "mother" in their name meant "main" (as in "motherboard") and there were less powerful "daughterboxes" related to them.
The sequel may answer this question, but since it seems that this plot point is taken from Justice League mythology, an answer from the comics is fine.