  A nontrivial scalar field configuration of vanishing energy-momentum is
reported. These matter configurations have no influence on the metric and
therefore they are not be "detected" gravitationally. This phenomenon occurs
for a time-dependent nonminimally coupled and self-interacting scalar field on
the 2+1 (BTZ) black hole geometry. We conclude that such stealth configurations
exist for the static 2+1 black hole for any value of the nonminimal coupling
parameter $\zeta\neq0$ with a fixed self-interaction potential $U_\zeta(\Phi)$.
For the range $0<\zeta\leq1/2$ potentials are bounded from below and for the
range $0<\zeta<1/4$ the stealth field falls into the black hole and is
swallowed by it at an exponential rate, without any consequence for the black
hole.
