But the flagella is different than the flagella that is found in eukaryotes. So the type of protein that our flagella is composed of inside prokaryotes is different than in eukaryotes. Now, prokaryotic organisms include two types of domains. We have bacteria and we also have archae. So basically, archae are single celled organisms that include those organisms that are capable of living in very harsh and hostile environments, such as very high temperatures, very high or very low PH, very high acidity, very salty, and so forth. So those organisms that can live in very hostile environments usually fall into domain known as rkey.