A seed crystal is a small crystal that is used as a base to grow a large single crystal. Without a seed, crystals form slowly from random intermolecular interactions. When the seed is placed in a saturated or supersaturated solution it acts as a nucleation site. This decreases the time needed to grow a crystal and directs growth to a single region. Here’s how to grow a seed crystal and how to use one to get a large, perfect crystal.

The semiconductor industry uses seed crystals to grow large single crystals (boules) of silicon using the Bridgman technique or Czochralski method. Seed crystals promote the growth of desirable type V crystals when tempering chocolate. Seeds are also used to grow crystals for crystallography and other purposes.

Virus Structure
X-ray crystallography is a tool used for determining the atomic and molecular structure of a crystal. The underlying principle is that the crystalline atoms cause a beam of X-rays to diffract into many specific directions

In virology. In 1935 tobacco mosaic virus became the first virus to be crystallized; in 1955 the poliomyelitis virus was crystallized.