NGC 5907 - Knife Edge Galaxy
50 Million light years from Earth in the constellation of Draco, this edge on Spiral galaxy is a bit of a mystery. The stars inside of it have very low metallicity, meaning they were created from a source of very pure hydrogen/helium, similar to what existed near to the big bang. This is often associated with very old objects, near to 11-12 Billion years old. Closer examination appears to show the galaxy has very few if any giant stars, most being dwarf stars, that are incredibly long lived (red dwarfs could theoretically last trillions of years).
Further more, more recent observations revealed a looping stream of stars and gas, following a tidal pattern which appears to show some interaction earlier in the galaxies existence.
The mechanisms involved that decide the size of the stars are not fully understood, so an entire galaxy of dwarf stars is quite a puzzle, not one we know to be replicated to this extent elsewhere.
One upshot of this is, that if the galaxy doesn’t interact with any others in the future, it’s likely to be among the last galaxies left standing, long after all other galaxies have been consumed by their central black holes, the dwarf stars will continue shining for billions more years before finally collapsing to white dwarfs or for the smallest of red dwarfs, a blue dwarf.