Volunteers were given sterile cotton swabs and were asked to insert the cotton swabs into their navels, to turn the cotton swab around three times and then return the cotton swab to the researchers in a vial that contained a 0.5 ml 10% phosphate saline buffer. Researchers at North Carolina State University, led by Jiri Hulcr, then grew the samples in a culture until the bacterial colonies were large enough to be photographed and then these pictures were posted on the Belly Button Biodiversity Project's website (volunteers were given sample numbers so that they could view their own samples online). These samples then were analyzed using 16S rDNA libraries so that strains that did not grow well in cultures could be identified. The researchers at North Carolina State University discovered that while it was difficult to predict every strain of bacteria in the microbiome of the navel that they could predict which strains would be prevalent and which strains of bacteria would be quite rare in the microbiome. It was found that the navel microbiomes only contained a few prevalent types of bacteria (Staphylococcus, Corynebacterium, Actinobacteria, Clostridiales, and Bacilli) and many different types of rare bacteria. Other types of rare organisms were discovered inside the navels of the volunteers including three types of Archaea (an organism that usually lives in only extreme environments) and two of the three types of Archaea were found in one volunteer who claimed not to have bathed or showered for many years. "Staphylococcus" and "Corynebacterium" were among the most common types of bacteria found in the navels of this project's volunteers and these types of bacteria have been found to be the most common types of bacteria found on the human skin in larger studies of the skin microbiome (of which the Belly Button Biodiversity Project is a part). (In these larger studies it has been found that females generally have more "Staphylococcus" living in their skin microbiomes (usually "Staphylococcus epidermidis") and that men have more "Corynebacterium" living in their skin microbiomes.) According to the Belly Button Biodiversity Project at North Carolina State University, there are two types of microorganisms found in the navel and surrounding areas. Transient bacteria (bacteria that does not reproduce) forms the majority of the organisms found in the navel, and an estimated 1400 various strains were found in 95% of participants of the study.