Finding tiny black dots scattered across your kitchen walls, baseboards, or floor can be unsettling, especially when they seem to appear overnight. One homeowner recently turned to a cleaning group online after discovering mysterious dark spots that looked like paint splatters. Despite mopping every day, the marks kept returning, leaving her puzzled and worried about what could be causing them. She posted photos, hoping someone had seen the same thing before.

The responses came quickly, and almost everyone agreed on the same explanation: spider droppings. While many people assume spiders leave behind tiny solid pellets, their waste actually looks very different. Instead of dry droppings, spiders leave small liquid stains that can resemble ink splashes. Knowing the difference can help you identify the source—and decide whether it’s time to look more closely around your home.