Why do crystals do crystals have room to grow in hollow areas?

Crystals have room to grow in hollow areas because these spaces provide an environment free from external pressure and obstructions, allowing for the unrestricted expansion of the crystal lattice. Additionally, the presence of fluids or gases in these hollow areas can facilitate the diffusion of the necessary ions or molecules needed for crystal formation. This combination of space and availability of growth materials enables crystals to develop larger and more intricate structures.