An unnamed robe-wearing platypus appears in a flashback told by Grandpa Fletcher. Dr. Phineastein and Ferbgor came across the platypus and it gave Ferbgor a steering wheel, which is ironic because they didn't mind that the platypus was walking like a human and selling them stuff. ("The Monster of Phineas-n-Ferbenstein") The episode says they were collecting spare parts from semi-aquatic mammals so this could mean there are more of them. This is the only time the robe-wearing platypus appears. It may be an ancestor of Perry . It should also be noted that the platypus looked around before handing Ferbgor the steering wheel. It seemed that the part trading he was doing was an illegal underground business.
- "The Monster of Phineas-n-Ferbenstein"(First appearance)