You LEFT a FIVE month old puppy LOCKED UP for EIGHT HOURS straight -in a crate????? You can't (or shouldn't) DO THAT! His bladder really can't be asked, to go more than 5 hours, MAXIMUM.
I do not even ask my ADULT dogs to go EIGHT HOURS with no potty break. - SO, ARE YOU INSANE or just thoughtless and/or abusive?
What you see, is something he either pulled INTO the crate while you were gone FOR EIGHT HOURS, or the remains of a pee pad if one was left in his crate. (Which I would hope you did not do - ONLY IDIOTS - EVER USE THEM, since it is a SCAM product) and virtually everyone knows -
1) not only do they NOT WORK....
when BORED, puppies can chew on them and
2) the absorbent material inside them is TOXIC, if consumed.
IF you have NO IDEA what he consumed, or which way this material came back OUT of him - GET TO AN EMERGENCY VET - if yours is closed.