Spiny bograts, a type of rat, were a species originally from the swamps found on the planet Dagobah. Yoda, the Jedi Grand Master, who was in exile on Dagobah, frequently had spiny bograts, along with other swamp creatures, enter his hut. He permitted all non-venomous beings to remain, providing him with companionship.
The reference book Ultimate Star Wars, published in 2015, was the first time that spiny bograts were referenced.