Filipovic et al. present the serendipitous radio-continuum discovery of a likely Galactic supernova remnant (SNR) G305.4–2.2. This object displays a remarkable circular symmetry in shape, making it one of the most circular Galactic SNRs known. Nicknamed Teleios (a Greek word meaning perfect or complete) due to its symmetry, it was detected in ASKAP Evolutionary Map of the Universe (EMU) radio–continuum images with an angular size of 22 x 21 arcminutes. While there is a hint of possible Hα and gamma-ray emission, Teleios is otherwise exclusively seen at radio–continuum frequencies. Interestingly, Teleios is not only almost perfectly symmetrical, but it also has one of the lowest surface brightnesses discovered among Galactic SNRs and a steep spectral index of –0.6±0.3. The best estimates place Teleios as a type Ia SNR at a distance of either ∼2.2 kpc or ∼7.7 kpc, depending on which spiral arm of our Galaxy it is located in. This indicates two possible scenarios, either a young (under 1,000 yr) or a somewhat older SNR (over 10,000 yr). With a corresponding diameter of either 14 or 48 pc, our evolutionary studies place Teleios at the either early or late Sedov phase, depending on the distance/diameter estimate. However, modelling also predicts X-ray emission, which we do not see in the present generation of eROSITA images. As all considered scenarios have their challenges, and no definitive Supernova (SN) origin type can be established at this stage. Remarkably, Teleios has retained its symmetrical shape as it aged even to such a diameter, suggesting expansion into a rarefied and isotropic ambient medium. The image above is the ASKAP radio image of Teleios in Stokes I (total intensity).