Iodine is a slightly rare halogen element that is highly reactive and somewhat toxic. Though it is also essential to life, is required for the synthesis of thyroid hormones. It is also heavily used in the treatment of endocrine and thyroid cancers and in antiseptic treatments.
The red lionfish is the largest of the lionfish. Its toxin relates it to iodine, as it’s not fatal to humans necessarily. The red lionfish is invasive in the Caribbean and other tropical Atlantic environs. It’s become a major pest in some areas, its capacity to breed quickly and lack of predators makes it particularly hard to control.
One of the most famous Nobel gasses Xenon is actually uncommon in Earths atmosphere. It’s mostly used in lighting, lasers and as a propellant in ion thrusters.
Geese are one of the largest birds species. Most are capable of flight and are migratory, though there are a few exceptions. There used to be giant flightless geese, most are now extinct. It is connected to Xenon by its flight and slightly uncommon nature.