Our feline friends have a rep for being cool as cucumbers. But even they can be hiding insecurities. Keep this in mind if you see a cat sucking wool.

Say what? That’s right—wool sucking in cats is a compulsive form of behavior that can be traced back to psychological trauma early in life. Specifically, most wool-sucking cats were forced to wean early on before they had the drive to eat solid food. Subsequently, their nursing behavior was displaced to materials that felt like Mom. You could compare it to a child sucking a thumb or a pacifier.

In most cats, wool sucking resolves over time, although it can recur with stress. But in other cats, the behavior may progress to eating—not just sucking—the comforting material. That’s when cat parents need to seek veterinary advice to avoid further problems.