Polymorph Any Object

[Lord Pendragon]

While I feel confident that I know how Polymorph Self and Polymorph Other work, I'm a little unsure about their high-level cousin, Polymorph Any Object.

Specifically, while the two lesser spells don't grant the hp of the new form, what about Polymorph Any Object? After all, this 8th-level spell is capable of transforming a pebble into a human being for a short period of time. During that time, does the creature have the hp of a human or a pebble? If so, what are the hp of a pebble? Or any of the hundreds of other inanimate things which could be polymorphed with this spell?

The description starts off with, "as Polymorph Other except..." and doesn't mention hp, which would lead me to believe hp aren't changed. Yet with the breadth of transformations allowed by what is after all an 8th-level spell, I'm not sure it makes sense to not allow the hp of the new form.

Thoughts?

 

[Iku Rex]

With Polymorph Other the HPs don't change, but with Polymorph any Object it's more unclear.

The problem is that objects can have insane amounts of hit points. It would be silly if you could create a mouse with 10000 hit points by starting with a huge slab of rock.

My take:

Objects have hit points based on size and hardness. (PHB page 136)
Creatures have hit points based on hit dice and constitution. (PHB page 119)

If you change a creature into another creature, the hps remain unchanged (as per Polymorph Other).

If you change a creature into an object, it becomes an object and follows the rules for objects (hp based on size and hardness).

If you change an object into a creature, it becomes a creature and follows the rules for creatures (hp based on hit dice and constitution).