bottom type of quark
Bottom quarks or beauty quarks are the second most massive of the elementary particles (particles that are so small that they can not be divided any more). All quarks are elementary particles. Bottom quarks have a charge of -1/3, similar to down quarks. Although bottom quarks are not very common, they are found in particles such as B mesons, among others. All bottom quarks will decay into charm quarks or up quarks in about 10–12, due to weak force.