What kind of liner is this?

[Pablo]

Just received an M40 Q64 helmet, but the liner doesn't look right. The leather seems textured. Any info would be greatly appreciated. Thanks.

[helmet2id]

It is a pig skin liner. It is good, but unfortunately, seems to be dry and has some blood rot. Jim G.

[Pablo]

Thanks Jim. Blood rot? I found this ding and crack in the helmet. Do you think this may have contributed to the blood rot, although it did not penetrate the helmet?

[SteveR]

The helmet has had water in it which has caused rust and discoloration and hardening of the leather.