  Ice crystals growing in highly supersaturated air at temperatures near -5 C
exhibit a distinctive, nonplanar dendritic morphology that has not been
previously documented or explained. We examine this structure and identify its
most prominent features in relation to the ice crystal lattice. Developing a
full 3D numerical model that reproduces this robust morphology will be an
interesting challenge in understanding diffusion-limited crystal growth in the
presence of highly anisotropic surface attachment kinetics.
