The original, living Muffit is killed by falling debris in a major city on Caprica during the Cylon sneak attack. Boxey mourns for Muffit on the Rising Star, refusing to eat as a result (TOS: "Saga of a Star World").
To ease Boxey's emotional suffering, his future stepfather Apollo asks Dr. Wilker to furnish a prototype robotic daggit, called the Muffit II. As no daggits have survived the sneak attack, there is a genuine need for replacement daggits, as they had played numerous roles in Colonial society, including that of domesticated pet, watch animal, and tracker. In order to train Muffit II, Wilker scans an image of Boxey into its circuits for imprinting purposes, thus allowing Boxey to train the robot.
Muffit accompanies Boxey to the surface of Carillon, and runs out of the landram near a rich tylium deposit. Boxey and Muffit are "kidnapped" by the Ovions, but are later turned over to Apollo and Serina by the Queen of the Ovions. When Starbuck and Apollo are discovering the Ovion plot, Boxey ends up chasing Muffit out of the elevator, and is nearly killed by a sword-wielding Centurion. The warriors intervene, and as a result end up finding and rescuing Cassiopeia. During the ensuing escape and conflict with the Cylons, Muffit helps to destroy a Centurion by tearing into its leg (TOS: "Saga of a Star World").
Muffit stows away in the snowram with Boxey in order to be able to see the snow on the surface of Arcta. When the snowram is disabled and the commando team nearly succumbs to the effects of the diethene storm, Muffit exits the snowram and wanders off. They fear that Muffit might attract the attention of Centurions trying to find them. They eventually pass out due to the diethene, but awaken to discover that Muffit had brought some Thetas back to the snowram, saving the team and the mission (TOS: "The Gun on Ice Planet Zero, Part I").
When an expedition is sent to Serenity to trade for agricultural supplies, Boxey and Muffit are allowed to join the landing party. Siress Belloby is kidnapped by the Borays, so Apollo uses Muffit to track her scent back to the main camp of the Borays, where an agreement is brokered with their leader (TOS: "The Magnificent Warriors").
Among other things, including the ability to wave (TOS: "The Gun on Ice Planet Zero, Part I"), Muffit is trained by Boxey to "sniff" out mushies. This ability comes in very handy when Boxey, Boomer and Athena are stranded in Galactica's rejuvenation center. Muffit is able to sniff out the mushies placed on the bridge, and thereby negotiate a convoluted, maze-like path through the ship's ventilation ducts to retrieve gravely needed lifemasks. Later, Muffit returns to the fire-engulfed duct system to save the life of a fallen firefighter (TOS: "Fire in Space").
- Peanuts is apparently the name of the dog who portrayed the original living daggit in the scenes on Caprica.
- Muffit II was played by a chimpanzee named Evolution, who is referred to by the nickname of "Evie the Chimp".
- The Muffit "hero" suit used in the series still exists and was presented for auction on August 1, 2005. It remains the only known Muffit costume still in existence.
- The costume itself consists of servos to animate both the spinning ears and to move the mouth, controlled by a wireless remote control to animate these functions. The tail itself is a high-gauge spring, which bounces as Evolution moved.
- The costume was created by John Dykstra and his team at Apogee.
- When performing long takes that did not require movement, the production crew would place a custom articulated form inside the suit.
- The character "Muffit" was also given a nod in the children's book Muffit's Really Big Adventure depicted in the short-lived Caprica series. (CAP: ?, Propworx blog post).