  We define the concept of a partial translation structure T on a metric space
X and we show that there is a natural C*-algebra C*(T) associated with it which
is a subalgebra of the uniform Roe algebra C*_u(X). We introduce a coarse
invariant of the metric which provides an obstruction to embedding the space in
a group. When the space is sufficiently group-like, as determined by our
invariant, properties of the Roe algebra can be deduced from those of C*(T). We
also give a proof of the fact that the uniform Roe algebra of a metric space is
a coarse invariant up to Morita equivalence.
