Petri dish cultures are plastic containers that hold nutrient-rich agar and are inoculated with mushroom mycelium. Agar is simply a type of gelatin that provides a semi-solid surface for the mycelium to grow. We mix in nutrients to provide food for the fungus. The mycelium rapidly colonizes the agar dish, and these are used to expand the culture to other dishes or to inoculate grain jars for cultivation. We sell fully-colonized petri dishes of a wide range of mushroom species from around the world. Dishes are 100mm in diameter by 15mm tall. We sell sterilized dishes that you can pour your own agar into, and we also offer pre-poured agar dishes. Dishes come in lots of 20.