And it’s a USB! Well, that’s what Science Daily says it’s made of, anyway. It’s formally called a “Xi_b^*” and it’s just been spotted at the Large Hadron Collider:
In the course of proton collisions in the LHC at CERN, physicists Claude Amsler, Vincenzo Chiochia and Ernest Aguiló from the University of Zurich’s Physics Institute managed to detect a baryon with one light and two heavy quarks. The particle Xi_b^* comprises one “up,” one “strange” and one “bottom” quark (usb), is electrically neutral and has a spin of 3/2 (1.5). Its mass is comparable to that of a lithium atom. The new discovery means that two of the three baryons predicted in the usb composition by theory have now been observed.
The discovery of the new particle confirms the theory of how quarks bind and therefore helps to understand the strong interaction, one of the four basic forces of physics which determines the structure of matter.