  We report a novel surface-tension driven instability observed for droplets
spreading on a compliant substrate. When a droplet is released on the surface
of an agar gel, it forms arms/cracks when the ratio of surface tension gradient
to gel strength is sufficiently large. We explore a range of gel strengths and
droplet surface tensions and find that the onset of the instability and the
number of arms depend on the ratio of surface tension to gel strength. However,
the arm length grows with an apparently universal law L ~ t^{3/4}.
