Morpholomew is very curious, as seen when he chased a noise which turned out to be a rabbit. He is also one of the few experiments that demands payment, which he considers to be chicken legs. He enjoys chicken legs so much that he can easily go through several buckets of them in only a few minutes. While he is cautious of others at first, he is friendly and trusting, as he immediately befriended Stitch after the latter pursued him and pronounced him his cousin and ally, even shaking hands. He is fairly relaxed and doesn't mind helping people. He also seems to have a sense of humor, as he once changed Gantu into a harmless bunny.
Experiment 316 was the 316th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to morph organisms into any other organism. 316 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai, with 316's pod landing on a hay umbrella.
At the very beginning of the episode, Lilo decided to enter the local skateboarding competition in order to win a brand new skateboard, the Velociraptor 1200, for her crush Keoni. Before the event, she and Stitch discovered Experiment 316, whose pod was activated in a fountain after Stitch unstuck Lilo's skateboard from a straw umbrella. According to Jumba, Experiment 316, or Morpholomew, was a creature capable of giving anyone the appearance of someone else. Lilo used this power in order to enter the competition as Keoni.
In the meantime, Jake, Lao Shi, Fu Dog, Trixie, and Spud arrived at the Kauai skate park. They were looking into reports of undisguised magical creatures lurking on the island of Hawaii (actually Jumba's illegal genetic experiments), although Jake was more interested in winning the contest's grand prize. All of them separated to go on their own business: Lao Shi became enamored with Mrs. Hasagawa; Trixie and Spud headed to the beach; Fu Dog went to place some bets on Jake while the latter signed up for the skateboarding competition.
Lilo did the same, but soon realized that impersonating Keoni was likely a bad idea when she earned a low score. She asked Morpholomew to change her into absolutely anybody else so she could start over, but registrations closed before she got a chance to sign up again.
Elsewhere, Jake, having spotted Morpholomew with Lilo and mistaking the little red blob for a magical creature, transformed into the American Dragon and got ready to pursue them. However, he was captured by Gantu, who mistook him for Morpholomew. Since Jake didn't show for the competition, Lilo decided to ask Morpholomew to turn her into Jake so she could enter in his stead.
Meanwhile, Jake managed to escape Gantu's ship before he was transferred to Hämsterviel's asteroid and went back to the skate park. However, Lilo had already taken his place and failed once again to score any points. Trixie and Spud grew suspicious of Lilo (still disguised as Jake) while she threw a tantrum when Stitch told her that Morpholomew (who earlier got distracted by a rabbit) had been captured by Gantu. They knew something was up when Lilo panicked upon hearing Fu Dog speak. The real Jake (in his dragon form) arrived at that moment and engaged in a duel with Stitch. Before things got too far, Lilo managed to calm everyone down and explain the whole situation.
Once everything was clarified, everyone decided to team up to retrieve Morpholomew. They traveled over to Gantu's ship and fought against him for Morpholomew. In the confusion, Jake and company tricked Gantu into thinking he captured Morpholomew, when in reality Spud assumed the little red blob's form and got kidnapped instead. Thanks to this, the team managed to get Morpholomew back and change Gantu into a little white bunny as punishment for all the trouble he caused.
The gang then headed back to the skateboard competition, where the winner claimed the Velociraptor 1200. Jake and Lilo were a bit bummed out by this, but were happy to have made new friends. They left on good terms and promised to see each other again soon. Meanwhile, Morpholomew was given a one true place at a costume store, where he morphed people into celebrities according to the photo he was shown.
Morpholomew was seen early in the movie morphing the Ice Cream Man into the famous Elvis as Lilo was making her rounds with Scrump to make sure all the experiments were happy in the one true place they belonged.
Later, the first 624 experiments, including Morpholomew, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
It is unknown whether or not Morpholomew participated in the following battle between the experiments and the Leroy clones.
The Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
Morpholomew made an appearance in the Stitch! anime, where he was modified by Hämsterviel to morph his own body instead of others, and was given a vocabulary. At an unknown time after this, Lilo, now an adult, took a vacation with her daughter, Ani, to an island in Japan where, unbeknownst to them, Stitch resided at the time. Ani met Stitch, who mistook her for a de-aged Lilo, and they played together happily. Hämsterviel took advantage of this and sent Gantu to use Morpholomew to take the image of her and distract Stitch long enough to capture him.
- Morpholomew is one of the ten known experiments named by someone other than Lilo, the other nine being Gigi, Elastico, Yaarp, Hammerface, Heat, Thresher, Plasmoid, Shrink, and Leroy.
- Morpholomew greatly resembles Morph from Treasure Planet in form, color, and that they both have shapeshifting powers.
- Morpholomew is one of the rare experiments to turn from bad to good the fastest, as once Stitch introduced himself as his cousin, Morpholomew quickly reformed.
- Lilo initially planned to name 316 "Changer", but Trixie convinced her that he should have a better name, with Spud being the one to name him "Morpholomew".
- His name may be a reference to the apostle Bartholomew.
- When Jake Long was in his dragon form, he was mistaken for Morpholomew by Gantu.
- Morpholomew's pod color is yellow.
- Morpholomew is described by the experiment computer screen as, "Experiment 316. Primary function: Shapeshifter."
- Morpholomew is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.
- Morpholomew is the only experiment from a crossover episode that appeared in the Stitch! anime.