Is this little “bag” stuck to the wall? This isn’t dirt, this is a butterfly!

What exactly is this? It’s not eggs or dirt. This is the caterpillar of a small butterfly that has built itself a “mobile home.” 🏠 Why does it have this sac? For protection: It builds its sac from silk, dust, carpet fibers, and anything small it can find. It becomes like a small stone. For camouflage: It’s gray like a wall, so it’s never visible. Its head is down: The golden/brown part that’s visible underneath is its head and legs. When it wants to walk, it only sticks its head out and drags the sac behind it. When it senses danger, it hides completely inside the sac and closes the door. Is it dangerous or does it bite? Not at all. It doesn’t bite and doesn’t do anything to humans. It doesn’t transmit any diseases. But its problem is:
The caterpillar eats. And what does it eat? Fabrics, carpets, wool, pillow feathers, and even dead spiders. If you leave them for too long, they’ll damage your woolen clothes or carpets. Why do they come to your house? One sign: dampness + dust + spiders.