Thank you! I have looong time looked for so good explanation. So the right answer is that large cracks are not too numerous, and fortunately you will not find

Thank you! I have looong time looked for so good explanation. So the right answer is that large cracks are not too numerous, and fortunately you will not find such artifact under your bed. Even more - if I understand right, they are fragile, and cannot survive in places with high gravitational wave activity, like galaxies. So we should search them in old voids, where they only trouble each other, and nothing else intervene. This is acceptable start point for research, but with huge drawback: this assume very expensive research, because only largest telescopes (or latest gravity wave detectors) have good chances to detect anything.