By this time of year, you probably think you’ve seen all of the pumpkin things that could ever exist: pumpkin pie, pumpkin candles – there’s even pumpkin spice spam. But you might not have seen a pumpkin toadlet (Brachycephalus ephippium). These weird and wonderful amphibians are native to eastern Brazil and are small enough to fit on a penny.

This year, scientists discovered that the toadlets (like some chameleons) have bones that glow! Although fluorescent bones are not unique to these toadlets, thin, light-colored skin combined with bones that are “exceptionally fluorescent” compared to closely related species means that the glow can be seen in living animals.

Scientists don’t know why the pumpkin toadlets evolved this way, but they have a few guesses. These fluorescent bones might be used as visual communication – pumpkin toadlets rely heavily on vision due to underdeveloped ears. In fact, researchers showed that they appear to be unable to hear their own high-frequency mating calls! Another hypothesis is that the fluorescent bones serve as a warning to predators that the toadlets are highly toxic.