Everyone’s aware about Black holes, but few people suspect there’s a hypothesis about White holes
Following from the name, White holes are the opposite of black holes. If black holes as if "suck" all surrounding space into themselves, white holes "spit it out".
White holes are unstable. In the process of formation of matter in them the gravitational forces grow and at some point collapse the object, turning it into a black hole.
It is possible that all the white holes formed immediately after the Big Bang are now literally dead, so we do not see them.