  We have identified spectral features in the late-time X-ray afterglow of the
unusually long, slow-decaying GRB 130925A using NuSTAR, Swift-XRT, and Chandra.
A spectral component in addition to an absorbed power-law is required at
$>4\sigma$ significance, and its spectral shape varies between two observation
epochs at $2\times10^5$ and $10^6$ seconds after the burst. Several models can
fit this additional component, each with very different physical implications.
A broad, resolved Gaussian absorption feature of several keV width improves the
fit, but it is poorly constrained in the second epoch. An additive black body
or second power-law component provide better fits. Both are challenging to
interpret: the blackbody radius is near the scale of a compact remnant ($10^8$
cm), while the second powerlaw component requires an unobserved high-energy
cutoff in order to be consistent with the non-detection by Fermi-LAT.
