https://zoom.us/j/97377192005?pwd=OUZPR1Z3ZGc5WDZPYW1SakEzV1pvQT09 In 2018 our group identified a large, diffuse galaxy that looked unlike any previously known object. It appeared to have a population of strange, very luminous globular clusters and - even more puzzling - appeared to lack any dark matter. Three years and a lot of controversy later the mystery has only deepened. I will present the latest findings from extremely deep Hubble images as well as new data from the Dragonfly Telephoto Array, the telescope that we are using to find low surface brightness emission. I will also touch on the implications for galaxy formation and the nature of dark matter. The talk will end with a preview of a major upgrade of the Dragonfly telescope. Prof. van Dokkum is hosted by Diederik Kruijssen (kruijssen@uni-heidelberg.de)