  An intriguing, growing class of planets are the "super-puffs," objects with
exceptionally large radii for their masses and thus correspondingly low
densities ($\lesssim0.3\rm\,g\,cm^{-3}$). Here we consider whether they could
have large inferred radii because they are in fact ringed. This would naturally
explain why super-puffs have thus far only shown featureless transit spectra.
We find that this hypothesis can work in some cases but not all. The close
proximity of the super-puffs to their parent stars necessitates rings with a
rocky rather than icy composition. This limits the radius of the rings, and
makes it challenging to explain the large size of Kepler 51b, 51c, 51d, and 79d
unless the rings are composed of porous material. Furthermore, the short tidal
locking timescales for Kepler 18d, 223d, and 223e mean that these planets may
be spinning too slowly, resulting in a small oblateness and rings that are
warped by their parent star. Kepler 87c and 177c have the best chance of being
explained by rings. Using transit simulations, we show that testing this
hypothesis requires photometry with a precision of somewhere between ~10 ppm
and ~50 ppm, which roughly scales with the ratio of the planet and star's
radii. We conclude with a note about the recently discovered super-puff HIP
41378f.
