yes
There are no animals today that look anything like Stegosaurus. If there were, it might be easier to determine what Stegosaurus's plates were used for.
There are no animals today that resemble Stegosaurus. That is one reason why it is so difficult to figure out what their plates were used for.
Stegosaurus, like all land animals, obtains oxygen by inhaling air. They did have nostrils and a mouth, and they could breathe through those openings.
Like other land vertebrates, Stegosaurus would have inhaled and exhaled through its nostrils and sometimes its mouth.
Animals like humans have a brain, why should they have any other living thing? Please clarify what your question is.
Smaller animals like bacteria and plankton.
Stegosaurus was herbivorous and had a spiked tail. There were some other dinosaurs similar to Stegosaurus, but Stegosaurus itself was probably the most common dinosaur we know of that has a spiked tail.
Stegosaurus was a large herbivore that probably ate mosses, ferns, horsetails, cycads, and conifers that grew within three feet of the forest floor. Like other large herbivores, the role of Stegosaurus in its ecosystem was to prevent plant overgrowth. They also helped to recycle nutrients via their urea and feces. Last but not least, they provided food for animals farther up the food chain, such as Allosaurus, Torvosaurus, and Ceratosaurus.
Tetrapod refers to any terrestrial vertebrate. That includes amphibians like frogs, reptiles like dinosaurs, including Stegosaurus, birds, and mammals, including humans.
A baby stegosaurus is commonly referred to as a "hatchling." Like other dinosaur species, stegosaurus hatchlings would emerge from eggs laid by their mothers. These young dinosaurs were likely quite vulnerable and would rely on their parents for protection and nourishment in their early stages of life.
Baby Stegosaurus would have made an easy meal for almost any carnivorous dinosaur, even small ones like Ornitholestes. However, Stegosaurus lived in herds and the parents would have done their best to protect the youngsters. Adult Stegosaurus had predators too, though. Carnivorous dinosaurs large enough to hunt adult Stegosaurus include Ceratosaurus, Torvosaurus, Allosaurus, Epanterias, and Saurophaganax.
We know very little about Stegosaurus behavior. What we do know is that they were herbivores, and that they lived in multi-aged herds with juveniles and adults. This suggests that Stegosaurus raised their offspring.