The recent discovery of the XYZ states -- a series of hidden charm/bottom resonances that do no fit into the traditional hadronic spectrum -- has opened new vistas in hadronic spectroscopy. Among the theoretical explanations available, the bound state / molecular interpretation of the XYZ states is particularly interesting. From a theoretical perspective we expect hadronic molecules to be extremely symmetric. Hence we can easily relate the properties of known molecules and predict the existence of so far unobserved states. Probably the most obvious candidate to be molecular is the famous X(3872), but the list of molecular candidates also include the recently discovered Z_b(10610), Z_b(10650), Z_c(3900) and Z_c(4020), though they are not yet stablished as molecular and competing explanations also exist. In this talk I will explain the relationship among the spectroscopy of the molecular states and heavy quark symmetries by using the effective field theory formalism. I will also explain why the molecular hypothesis suggest that the recently discovered Z_c's are probably the heavy flavour partners of the Z_b's, what is the probable mass of the bottom counterpart of the X(3872) and also why should be expect the existence of triply heavy pentaquarks from the assumption that the Z_b's are molecular.

References:
[1] M. Pavon Valderrama, PRD85 (2012) 114037.
[2] J.M. Nieves, M. Pavon Valderrama, PRD86 (2012) 056004.
[3] J.M. Nieves, C. Hidalgo-Duque, M. Pavon Valderrama, PRD87 (2013) 076006
[4] F.-K. Guo, J.M. Nieves, C. Hidalgo-Duque, M. Pavon Valderrama, PRD88 (2013) 054007
[5] F.-K. Guo, J.M. Nieves, C. Hidalgo-Duque, M. Pavon Valderrama, PRD88 (2013) 054014