Typically, these kinds of stories might touch on themes like social neglect, degradation, and the consequences of extreme circumstances. But please be aware that this is a very sensitive and potentially disturbing topic.
Good animal short stories often have vivid characterizations of the animals. For example, in 'The Wind in the Willows', the animals like Mole, Rat, Badger, and Toad are all very distinct in their personalities. Mole is shy and curious, Rat is friendly and hospitable, Badger is wise and solemn, and Toad is impulsive and vain.
I'm not sure there are common stories specifically about 'anal egg burying' in a general sense in typical animal behavior. However, some animals like certain reptiles bury their eggs in the ground for incubation. But this has no relation to the 'anal' aspect which seems rather an odd or made - up concept in this context.
The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.
In many places, 18+ porn comics are considered illegal. This is because they can have a negative impact on society and violate moral and legal standards.