I am leading a survey of the carbon dioxide content in super-Jupiter planets with JWST. I used a unique coronagraphic mode I pioneered on the HR 8799 system to observe four new directly imaged single planet systems with masses ranging from 1 to 15 times the mass of Jupiter, in order to understand how these giant planets form. The first of these observations genuinely shocked me: we found a strong CO2 signature in an exceptionally massive planet, 29 Cygni b. This world is about 15 times the mass of Jupiter, but this much CO2 indicates that 29 Cyg b may have accreted more than 100 times the mass of the Earth in carbon and oxygen rich ice during its formation. This work was published in the Astrophysical Journal Letters here, and had a NASA press release, found here. This strange “hyper-giant” planet shows us that planets can form and grow to sizes beyond the deuterium burning limit (at about 13 times the mass of Jupiter), where they can ignite a limited fraction of heavy hydrogen in a fusion process within their core. This poses a significant philosophical question: do we define planets taxonomically, by their mass, or holistically, by their formation?