The appearance of a flying skull is that of a skull with a red, bat-like wing on each side and glowing red eyes.
In game, flying skulls appear flying around in various patterns. When the bird touches one, he will die and respawn. Flying skulls can be defeated if the player fires a snowball at them and freezes them, or if the player makes an already frozen flying skull fall on another. If a flying skull falls to the ground frozen, it will break and leave a snowball behind on the ground. This can be useful when trying to activate switches that are on the ground.
A frozen flying skull
A rock that appears to look like a flying skull, from level three
The icon artwork depicts them with more bird-like wings than the bat-like ones they have in game.
On level three, there is a rock that looks like a sideways flying skull.
In level 13 of Super Stock Take, the Nitrome Boss says "The new flying enemies are dumb... Seriously, a skull with red bat wings?! Bring back the old one!" which may be a reference to the flying skulls.