Its mass of 178 GeV is vastly greater than any other fundamental particle known and is the reason it took so long to discover.  
Identification of this particle rest almost entirely upon location of secondary vertices from decays of b-quarks because its lifetime is far too short for any hadronization to occur.  This is because the Standard Model predicts that it decays into a W boson and a b quark nearly 100% of the time.  Its mass of 178 GeV is vastly greater than any other fundamental particle known and is the reason it took so long to discover.  FTP, name this sixth and last-discovered quark, the companion of the bottom.
Identification of this particle rest almost entirely upon location of secondary vertices from decays of b-quarks because its lifetime is far too short for any hadronization to occur.  
top quark (or t-quark or truth particle)