Preheat the oven: Preheat your oven to 400°F and line a sheet pan with parchment paper so the meatballs and dough don't stick.
Mix the meat mixture: In a large bowl, combine ground beef, panko, egg, garlic, onion, soy sauce, rice vinegar, Italian seasoning, salt, and pepper. Mix gently with your hands just until combined; overmixing makes the meatballs tough.
Shape the meatballs: Roll the mixture into 1.5-inch balls, about 24 total, and place them a few inches apart on the prepared sheet pan.
Pre-bake the meatballs: Bake the meatballs for 10 minutes so they firm up and release excess fat before you wrap them. Remove from the oven and let them cool for a few minutes so the dough is easier to handle.
Cut the dough strips: Unroll the crescent dough and press the seams together, then slice it into thin strips about 1/4 inch wide.
Wrap each meatball: Crisscross two or three dough strips over each meatball, leaving a small gap near the top for the eyes. Press the ends gently underneath so they hold during baking.
Add the eyes: Dot two tiny marks of mustard into the gap on each mummy, or press in two small pieces of olive for the eyes.
Bake until golden: Return the tray to the oven and bake for 10 to 12 minutes, until the dough strips turn golden brown and the meatballs reach 160°F in the center.
Warm the marinara: While the mummies finish baking, warm the marinara sauce in a small saucepan over low heat or in the microwave in 30-second bursts.
Serve warm: Arrange the mummy meatballs on a platter with the warm marinara in the center for dipping and serve right away.