Almost looks like it was fragged, the skeleton cracked and someone put a "cast" of epoxy putty over the break to hold the skeleton in place until it healed?
Otherwise, if it isn't a sponge then I have no other guesses at what I am looking at.
Almost looks like it was fragged, the skeleton cracked and someone put a "cast" of epoxy putty over the break to hold the skeleton in place until it healed?
Otherwise, if it isn't a sponge then I have no other guesses at what I am looking at.