You more than likely have animals in your walls o.
Attic animals droppings.
The droppings and urine can act as a vector for disease such as leptospirosis salmonella infection raccoon roundworm hookworm cryptosporidiosis and more.
Also nesting material is the most common with squirrels in the attic.
The most common type of animal droppings found in the home are from rats mice raccoons opossums squirrels birds geckos and occasionally skunks.
Animal droppings in the home are a sign that you have some sort of uninvited wildlife getting into your home and it must be addressed immediately.
Opossum droppings in the attic are very abundant when they live up there but that s not as common as with raccoons or rats.
The most common waste cleaned from attics is raccoon feces and after that probably rat poop and then after that squirrel waste is the most common.