Yup, seen that a few times. Still pops up every now and again on quite recent horns that have been repaired.
I've even used it myself - for repadding period clarinets, where its use would be in keeping with the techniques of the day.
It seems to vary considerably in stiffness. Most of its rather like beeswax, but I've seen some that's glass-hard. Probably had a lot of carnuba wax in it.