Industry converts 70 million tonnes of nitrogen into fertilisers every year. Fertilisers are added to the soil to replace lost nutrients and help crops to grow. This means it's liquid, not solid at low temperatures, so you can immerse things in it.
Liquid nitrogen is used to do experiments at low temperatures.
Animal embryos are stored in liquid nitrogen. Some people have even paid for their bodies to be frozen in liquid nitrogen after they die, in case one day a way is found to bring them back to life. Some fish cannot survive in acid waters. The average person contains almost 2kg of proteins. Your skin, your hair, and your fingernails, are all made from proteins.