My baby won't let go of her wooden block! She's held it the whole morning and cries when I take it. Will clutching it for such a long period of time cause harm to her hand/joints?

Your baby is so cute. My 2 years old boy also carries his favorite toy with him all the time, even during sleep he will wake up to look for them too. I think it is fine for kid to hold something in hand unless the stuff is sharp and heavy which will cause danger to the baby himself and other people.