Preheat the oven to 400 degrees. In a mixing bowl combine the ground beef, breadcrumbs, egg, garlic powder, salt, and black pepper. Mix until evenly blended.
Shape the mixture into 8 meatballs and place them on a baking sheet. Bake for 15 minutes.
While the meatballs bake, pour the marinara sauce into a skillet and heat over medium. Once the meatballs finish baking, add them to the sauce and let them simmer for 10 minutes.
Bring a large pot of salted water to a boil. Cook the spaghetti according to package directions, then drain.
Divide the spaghetti among four plates. Spoon sauce and two meatballs over each portion. Press two black olives into the top of each meatball to form eyes.