According to the sort of bad joke usually reserved for Christmas crackers (and dads), polar bears don't eat penguins because they can't get the wrappers off. If this doesn't make any sense, chances are you're not familiar with the penguin biscuit, a chocolate biscuit similar to (but not quite as good as) a Tim Tam.
But before all those penguin biscuit lovers come chasing after me with pitchforks*, let me distract you with some other ways to keep your penguins and polar bears separated...
Those little penguins are just too small to clamber up onto the cake, but look lovely hiding on the edge of the pedestal (though it's harder to see that cake bunting from down there). Penguins on cakes aren't so very unusual, but baby penguins are certainly rarer (hopefully not from being eaten by polar bears).
Or you can hide in plain sight...
Miniature icebergs by Atsuhiro Hayashi via Teacups and Rain
These tiny sculptures have a transient beauty a little like clouds - they must be so tricky to make before they melt.
Maybe the trick to keeping the penguins safe from the polar bears is to eat them up before they get the chance!
* I really mean people who love penguin biscuits, but penguins who love biscuits in general might be getting jumpy as well!