A Defiant-class Starfleet ship commanded by William Boimler for Section 31, crewed by people gathered from alternate realities and sent to trace the cause of the quantum fissures.
The USS Anaximander is a Defiant-class ship that appears in the Lower Decks episode Fissure Quest. Its captain is William Boimler, the transporter duplicate of Brad Boimler, who faked his death to work for Section 31.
The ship travels from one reality to another closing the fissures that have been opening across the multiverse. Its crew are castaways picked up on the way: a T'Pol, a Curzon Dax, a surgeon Elim Garak and his husband, a holographic Julian Bashir, and more than one Harry Kim.
Boimler, weary of endless variations on familiar faces, expects to find a villain. The trail leads instead to a ship of explorers commanded by an alternate Lily Sloane, whose drive is causing the damage by accident.