The Muses

The Muses were a set of nine clanks created 200 years ago by legendary master spark, Van Rijn for The Storm King. Tinka and Moxana were the only ones whose names and locations are known — until the destruction of Sturmhalten. However, in Chronology - Volume X, another (winged) clank appears who may be a Muse that Lucrezia Mongfish locked into a sub-basement of Castle Heterodyne. They may be the only surviving members, as the muses were an irresistible lure to other Sparks, who wished to disassemble them in order to find out how they worked. Since Van Rijn was exceptionally Sparky, this has not met with much success. However, an imperfect, but impressive copy of Tinka was built by Tarvek Sturmvoraus.

The picture on the west inner tympanum of Tarsus Hall of Transylvania Polygnostic makes them look as if they were intended to mimic the classical muses in form and function, although there is some doubt as to which classical muse corresponds to Moxana.

It is possible that the Enigma is one of the Muses (or, of course, another clank based on their design).

Outside World
Although writers accounted the Muses in Greek mythology as anywhere from one (Mousa) to three (Memory, Practice and Song) to four (Heart-delighting, Song, Beginning and Meditation) to seven to nine, eventually Hesiod, naming them, settled the count of nine Muses adopted by later Europan cultures. They were:

(The above information is excerpted from Wikipedia. See that article for more detail.)