Is cork safe for rabbits to chew on?

One person writes: Cork is a natural wood. Some rabbits may sometimes get a liking to it, and will start to chew on, as well as even sometimes swallow it. If it is untreated, then don't worry of this, your furry friend will be fine.

Another person writes: There is no information online that supports the above opinion. Cork does come from natural wood but it's also a processed material, so you can't say it's safe just because it's "natural." Cork is hydrophobic (water resistant), fire resistant, and elastic -- these properties suggest that it may not break down in the rabbit's belly, and things that don't break down in the belly are always a risk for rabbits, possibly leading to impaction, GI stasis, and death. Although there's no sources online that advise against it, there's also no sources that recommend it, so experts would advise "better safe than sorry": don't let your rabbit chew on cork. See the related questions below for more help.