this can be a lot of things, depending on how much gravity they produce. if there is a lot of gravity they could create a galaxy, star, or planet. if there is still lots of gravity, but not as much they could create a comet, asteroid, or dwarf planet. it all depends. Bu it can also be to do with what you mean by basic structures, and what the objects are.
rock can create asteroids, planets and parts of galaxies, gas, dust, ice and other things may create the rest and contribute to the other things.