adding a graphic to pack animals

[Manofdusk]

I've almost finished remaking a mod from an earlier version and I wanted to make Spelopedes into pack animals. I've got the functionality but when the spelopedes turn into pack animals, they turn into pink blocks. While I don't actually mind just using the base spelopede sprite for the pack animal version, I can't find where pack animal graphics are defined. I'm assuming that there's a def folder somewhere with a texpath I need to fill in for my mod but I can't locate it.

Anyone know?