In general, in prokaryotes the lifetime of mRNA is much shorter than in eukaryotes. Prokaryotes degrade messages by using a combination of ribonucleases, including endonucleases, 3 exonucleases, and 5 exonucleases. In some instances, small RNA molecules (sRNA) tens to hundreds of nucleotides long can stimulate the degradation of specific mRNAs by base-pairing with complementary sequences and facilitating ribonuclease cleavage by RNase III. It was recently shown that bacteria also have a sort of 5 cap consisting of a triphosphate on the 5 end. Removal of two of the phosphates leaves a 5 monophosphate, causing the message to be destroyed by the exonuclease RNase J, which degrades 5 to 3'.