  Efimov trimers are exotic three-body quantum states that emerge from the
different types of three-body continua in the vicinity of two-atom Feshbach
resonances. In particular, as the strength of the interaction is decreased to a
critical point, an Efimov state merges into the atom-dimer threshold and
eventually dissociates into an unbound atom-dimer pair. Here we explore the
Efimov state in the vicinity of this critical point using coherent few-body
spectroscopy in $^7$Li atoms using a narrow two-body Feshbach resonance.
Contrary to the expectation, we find that the $^7$Li Efimov trimer does not
immediately dissociate when passing the threshold, and survives as a metastable
state embedded in the atom-dimer continuum. We identify this behavior with a
universal phenomenon related to the emergence of a repulsive interaction in the
atom-dimer channel which reshapes the three-body interactions in any system
characterized by a narrow Feshbach resonance. Specifically, our results shed
light on the nature of $^7$Li Efimov states and provide a path to understand
various puzzling phenomena associated with them.
