Striders!! I've been trying to get a design down for them for a long time, and I think I may have found it!
Headcanons and design choices if you'd like to see them :)
Striders are somewhat avian in appearance, with pseudo-beaks and vestigial wings. Their feathers have become specialized over time to become more like sensory organs than anything else (like cat's whiskers), but they're also used to show emotions. Their long toes allow them to spread their weight across a larger surface area, which makes it easier for them to stay afloat in the less viscous areas of lava pools.
As for the little one, being covered in basalt is an issue especially prominent among overworked domestic individuals, as they're typically separated from their flock. Striders clean each other as a sort of bonding experience between mates or siblings, and keeping their legs clean keeps them from slowing down too much and sinking in to the lava beyond repair.
The egg shown is what's typical for a strider, and they usually only lay clutches of one. Similar to kiwi birds, they have a long incubation time and a larger size so the hatchlings come out nearly fully formed so they can leave the nest and be independent in about a week's time. Young striders tend to stick around their parents' territory for a year or so before leaving to find their own.
Also-- striders get very protective over their eggs when they're brooding! Any traveler in the Nether knows to steer clear of strider nests-- they pack quite a bite! Luckily, it's usually just angry displays at passersby rather than any physical injuries. Still, best to keep your distance...
