Unidentifiable (likely insect debris or droppings, such as flea dirt)

Indoors on household surfaces, flooring, or pet bedding

Varies based on organism; flea dirt consists of digested blood, while general debris or frass consists of organic matter

Appears as scattered small dark specks or smudges; if flea dirt, it turns reddish-brown when wet

Risks depend on source: flea presence indicates potential infestation and skin irritation to pets/humans; general insect frass can be an allergen