The Gallquin is a large, wormlike beast (which is nonetheless said to be a mutated "mud crab") which has a pair of targe tusks on either side of its head. It lives in the Swamps of Miregone and is the undeclared guardian of the Fifth Treasure of Rule. Ren and his crew had a run-in with the Gallquin upon their arrival in Miregone, when the monster attacked Tula. Ren and Ioz attempted to subdue the Gallquin by grabbing onto its tusks, unaware that the tusks can be fired as projectiles. They ended up in a big pool of mud for their troubles when the Gallquin fired its tusks (immediately growing a new set afterwards).
Slagon, the bio-transmuter, denied that the Gallquin was one of his creations, calling it "a true freak of nature," and informing Ren and his companions that the only way to kill the Gallquin would be to feed it the Loac Flower. The Gallquin later defended the Fifth Treasure from Bloth, Konk and Mantus, and although Ren, Ioz, Tula and Niddler had to use the Loac to heal their ailing bio-guide Roulette, Roulette repaid them by getting the treasure for them. Thusly, Ren was able to obtain what he sought without hurting the Gallquin at all.