When using diatom testing, scientists observe the amount of diatoms present on the organism and may be able to estimate a generalized time of death. If there are less than 20 different species of colonizing diatoms, then the organism's death could have been within the previous 7 to 12 days, but, if there are more than 50 different colonies of diatoms then it is determined that death possibly occurred several weeks ago. Certain taxa of diatoms narrow the time frame to more exact dates.