What the hell are these things?
According to Wikipedia, the caecilians are "an order of amphibians that superficially resemble earthworms or snakes." This means they are vertebrates with the complex brain and internal organ arrangement that implies, but as amphibians like frogs and salamanders they have both lungs and gills. It goes on to say, "they mostly live hidden in the ground, which makes them the least explored order of amphibians, and widely unknown."
They're sort of the amphibian equivalent of snakes. Snakes are lizards that lost their legs and learned to get along without them, and caecilians are apparently salamanders who did the same thing.
Feeding bodily tissue to their young is just an interesting new form of nursing: Processing nutrients into your body and then extruding it in such a way and form that your offspring can take them in efficiently with their limited capabilities. (However, only this one species of caecilian we're looking at right now does that.) Nice survival aid. Most cold-blooded vertebrates dump their eggs and let fate take its course.
They are the only amphibians that fertilize eggs internally, i.e. copulate. Most of them give birth to live offspring rather than laying eggs and in many species the newborns are fully developed rather than larval (e.g. tadpoles).
In many ways they seem rather advanced. Other than the part about not having legs, of course.
