  We convert a strongly interacting ultracold Bose gas into a mixture of atoms
and molecules by sweeping the interactions from resonant to weak. By analyzing
the decay dynamics of the molecular gas, we show that in addition to Feshbach
dimers it contains Efimov trimers. Typically around 8\% of the total atomic
population is bound into trimers, identified by their density-independent
lifetime of about 100~$\mu$s. The lifetime of the Feshbach dimers shows a
density dependence due to inelastic atom-dimer collisions, in agreement with
theoretical calculations. We also vary the density of the gas across a factor
of 250 and investigate the corresponding atom loss rate at the interaction
resonance.
