Yarn can help grow crystals by providing a textured surface for the crystals to adhere to as they form. The fibers in the yarn create a network that encourages nucleation, allowing crystals to develop in a more structured manner. Additionally, the yarn can hold the solution in place, ensuring that the conditions for crystal growth remain stable and consistent. This combination of surface area and stability makes yarn a useful medium for crystal growth experiments.
there are materials inside of the crystal to help them grow
Crystal's grow by a process called nucleation.
Well, unless you're a crystallographer or geologist, they don't really do much for you at all.If you're one of those, then the crystal shape can either help you understand how the crystals grow (for the former) or help you identify the mineral (for the latter).
Yes, you can steam acrylic yarn to help remove wrinkles and shape it.
yes
NO
A small quartz crystal can grow about 1mm a week assuming it is in a stable matrix.
a nucleus or plural nuclei
A crystal
how cold?
no
Yes, but not in the way that living things grow. Crystals are not composed of cells.