Seed crystal is a term used in crystallography to describe a small crystal that initiates the formation of a larger crystalline structure. Synonyms for seed crystal include nucleation site, embryo crystal, crystal nucleus, crystal seed, or primary crystal. In the field of materials science, seed crystals are also known as templates or germs. These are all terms used to describe the same phenomenon of small crystals being used to jumpstart crystal growth. Whether using a crystal nucleus in a laboratory setting or the germination of a seed in nature, the concept of seed crystal is critical to understanding how materials and natural processes develop.