Back again!
Hi, I've decided to add context to this question and my previous oneby providing how I'd think the environment would work, as well as the relationship between the host and terrarium inhabitant.
Nursery Nymphs
A species of animals that have evolved to have transparent 'nursery' like stomachs that hold plants and animals inside of them. Their stomachs grew to be transparent through the thinning of skin in order to attract mates as well as find a way to camouflage with their environment.
They have a symbiotic relationship with these plants and animals, where they provide a home and food for the terrarium inhabitant, while the terrarium inhabitant provides energy for the host.
To protect the internal organs it establishes a clear window of skin on the outerside of the organs The terrarium inhabitant helps break down food.
The terrarium also displays health and vitality, attracting mates.
These nymphs are bipedal as a way for advantage.
This is honestly just a silly species idea for a world but I really like it so far! Please tell me if this makes sense :)