What does it mean when my puppy has a dead toenail?

My 6 month old Maltese puppy has a dead toenail on his foot and it is black and it is not growing, it seems dead or something but I'm not sure what it is but what does it mean? Should I take him to a vet? It doesn't seem to be hurting him at all when I touch it nor whenever he walks. I love him with all my heart and I don't want this toe to do any damage to him in the future so please leave an answer Thanks~

It could just mean that that particular nail incurred some sort of trauma and/or the quick and nail became separated, so the nail portion "died". As long as it's not painful and you keep it trimmed so it doesn't get snagged on stuff, I wouldn't worry too much about it.