The discovery of numerous new charmonium-like structures since 2003 have revitalized interest in exotic meson spectroscopy. These structures do not fit easily into the conventional charmonium model, and proposals like four-quark states, hybrids and rescattering effects have been suggested as explanations. Since 2009, several new structures were reported in the J/ψφ mass spectrum with the following characteristics: they are the first ones reported decaying into two heavy mesons which contain both a cc pair and a ss pair; and their masses are well beyond the open charm pair threshold. Conventional cc states with a mass beyond the J/ψφ threshold are not expected to decay into this channel and the width is expected to be large, thus they are good candidates for exotic mesons. The focus of this paper is to review the recent developments on the structures in the J/ψφ mass spectrum from CDF, Belle and LHCb. Keywords: Exotic hadron; charmonium; exotic quantum number. PACS numbers: 14.40.Gx, 13.25.Gv, 12.39.Mk 1330020-1 Int. J. Mod. Phys. A 2013.28. Downloaded from www.worldscientific.com by GEORGE WASHINGTON UNIVERSITY on 02/05/15. For personal use only. K. Yi in the heavy quark sector, especially since the discovery of the X(3872) by Belle in 2003. 22-25 1.1. Recent developments of charmonium-like structures 1330020-3 Int. J. Mod. Phys. A 2013.28. Downloaded from www.worldscientific.com by GEORGE WASHINGTON UNIVERSITY on 02/05/15. For personal use only. 1330020-5 Int. J. Mod. Phys. A 2013.28. Downloaded from www.worldscientific.com by GEORGE WASHINGTON UNIVERSITY on 02/05/15. For personal use only.