called hermatypic coral.
If you mean why are they are not skeletons as a life form then the dull answer is that a living mammal needs a bloodstream and muscles, and tissue and so on. Most insects and spiders are basically skeletal.
double helix
No, there are no skeletons on the moon. The moon is a lifeless environment, so there are no living creatures (or skeletons) on its surface.
A group of Tigers that live together are called a pack.
If the group is a clone of organisms associated living together which haven't split after their formation, it's called a colony.
A group of similar individuals living together in an area is called population.
It was the skeletons/shells of living animals and plants.
A group of lions living together is called a pride.
The study of the structure of living things is called anatomy. It involves examining the physical characteristics of organisms, including their organs, tissues, and cells.
When you are talking about jelly under the ocean, you usually mean jellyfish. And jellyfish, like any other living organism, do have structures. They don't have skeletons, but they do have organized tissue.
Organ
A group of Chipmunks is called a "sweet" of Chipmunks! Isn't that cute?!