Cosmological correlation functions encode the spectrum of particles during inflation, in analogy to scattering amplitudes in colliders. Particles with masses comparable to the Hubble scale lead to distinctive signatures on non-Gaussianities that reflect their masses and spins. In addition, there exists a special class of partially massless particles that have no flat space analog, but could have existed during inflation. I will describe their key spectroscopic features in the soft limits of correlation functions, and discuss scenarios in which they lead to observable non-Gaussianity.