  We study the nature of charm degrees of freedom in hot strong interaction
matter by performing lattice QCD calculations of the second and fourth-order
cumulants of charm fluctuations, and their correlations with net baryon number,
electric charge and strangeness fluctuations. We show that below the chiral
crossover temperature thermodynamics of charm can be very well understood in
terms of charmed hadrons. Above the chiral transition charm quarks show up as
new degrees of freedom contributing to the partial charm pressure. However, up
to temperatures as high as 175 MeV charmed hadron-like excitations provide a
significant contribution to the partial charm pressure.
