It's almost surprising how often it is made in the shape of a piggy.
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A "svinokulebyaka" by meladan, posted in the LiveJournal community ru_piggy.
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A sliced piggy-kulebyaka accompanies a recipe on the Russian recipe site kuking.net ...
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This lovely kulebyaka was made by LarkinaL and posted on the photo community foto@mail.ru.
For an English-language recipe, check out Moti's Iraqi cuisine (he has a hammer and sickle variation).
Other popular non-abstract shapes include fish and crocodiles.