Child picks up feces

My  6 yr old son recently started picking up his own feces from the tpilet and hiding it in his room. I do not know where this  behavior comes from. He is a smart, kind normal little boy. What is this? Any light on the subject would be helpful. thank you

[Kevin Kennedy, Ph.D.]

What is he saying about this? Have you asked him about it? And, apart from this single behavior, is he developing well - in the family, in school, with his peers? Have there been any changes in his environment, particularly his social environment, in recent times?