Resi-goo

"Resi-goo" was Captain Liam Shaw's term for the organic matter left behind in a Changeling receptacle after a Changeling had regenerated in it.

While attempting to lure a rogue Changeling that was onboard the USS Titan-A in 2401, Commander Seven of Nine found a receptacle that did, indeed, contain "resi-goo," but it was destroyed before it could be scanned. (PIC: "No Win Scenario")