Leonardo, Donatello and others in “Unfinished Business”

It's a Neutrino baby. She must have come through a portal.

Here's a note. "Dear Ninja Turtles, please keep an eye on our Tribble. We'll dig you later, Gizzla and Zenter”. [While he’s reading, Tribble climbs out of the basket, onto the floor, and crawls away]

This diaper dudette must be their offspring.

They wouldn't have sent her unless there was real trouble.

Well, there's real trouble right here in Sewer City. Tribble has disappeared. Oh, great. Two minutes on the job, and we're blowing it."