A Petri dish (or Petri plate or cell culture dish) is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch. Glass Petri dishes can be reused by sterilization (for example, in an autoclave or by dry heating in a hot air oven at 160°C for one hour). For experiments where cross-contamination from one experiment to the next can become a problem, plastic Petri dishes are often used as disposables.
Modern Petri dishes often have rings on the lids and bases, which allow them to be stacked so that they do not slide off one another. Multiple dishes can also be incorporated into one plastic container to create what is called a "multi-well plate".