Most detectable sub-atomic particles are either "baryons" made of
three quarks, or "mesons" made of quark and an anti-quark pairs.
While the spectroscopy of dozens of known states fits this board
categorization of particles, the underlying theory of QCD allows other
configurations as well.  A "pentaquark" baryon contains four quarks
and one anti-quark.  Such states have been hunted without success for
over 30 years.  In recent months, however, experimental evidence has
been accumulating which shows strong evidence for a pentaquark with
"exotic" quantum numbers.  This has opened a new chapter in the study
of hadronic matter.  The talk will focus on recent work using the CLAS
detector at Jefferson Lab, but also discuss evidence from several
other laboratories.