I didn't realize that there was a such an issue with beard quills.
It freaked my players out when the first duergar they met pulled the quills from their beards and threw them. Made them seem inhuman and alien. Of course, this was the first time I have ever used a duergar in game, so they didn't know the difference.
I've thought about making a goblin druid who spends all his time in giant rat form -- or a guild of goblin thieves who are all druid-touched (but not in a sexy way, just the multi-class feat) and can change into giant rats.Perhaps Goblins could all have outsized incisors and rat-tails?
I did that with my undersea game; kobolds inspired by blue-dot stingrays, goblins inspired by goblin sharks, bugbears inspired by coelacanth, orcs inspired by black chimaera, and so on.This is an interesting approach to monster design that I've never considered -- merging characteristics with small mammals.
To which you reply "There is, now." Making stuff up is half the joy of DMing. I once added my own slime-mold creature, the Membrane; in puce, ecru, and vermillion varieties.A Blue Slime, which prompted this response - "there's no such creature!"