Here's a weird one for you: Huernia zebrina, the lifesaver plant. This is the first bloom for me.
So named because of the round shiny annulus in the center of the flower, as you can see. This is a succulent plant in the Stapeliae tribe, within the larger family containing milkweed and hoya and stephanotis (what a varied group!).
It looks like a cactus, but it's not prickly. It forms low clumps and creeps along the surface. The flowers are so thick and waxy that they look and feel like plastic, with amazing vibrant colors.
This group is pollinated by flies. Many stapeliads smell like carrion to attract them, though this particular species is relatively unscented. In fact, I haven't noticed any smell at all. Even if it does develop, the flower is cool enough for me to put up with a little stink.