Burst Bonds vs Black Tentacles

[thistledown]

Tentacles have caught you. You cast burst bonds. What happens?

Burst Bonds:

You blast your restraints with divine wrath, dealing 1d6 points of damage per caster level to the target object (maximum 5d6), ignoring hardness of 10 or less. A Fortitude save halves the damage, although only magical restraints receive a Saving Throw.

You can also target a creature that is grappling or otherwise restraining you (such as by adhesive or the swallow whole ability) with the spell. You don't need to make a touch attack to use burst bonds against a creature, and you can cast this spell without making a concentration check while grappled or pinned. The creature does not take damage as above. If you are grappled and your target fails its save, you may make an immediate attempt to break the grapple (but not reverse it) as a free action, with a +1 luck bonus to your CMB per caster level (maximum +5). If the target creature fails its save and you are restrained by an ability that originally allowed a Saving Throw, burst bonds allows a new Saving Throw with a +1 luck bonus per two caster levels (maximum +5).

Black tentacles:

This spell causes a field of rubbery black tentacles to appear, burrowing up from the floor and reaching for any creature in the area.

Every creature within the area of the spell is the target of a combat maneuver check made to grapple each round at the beginning of your turn, including the round that black tentacles is cast. Creatures that enter the area of effect are also automatically attacked. The tentacles do not provoke attacks of opportunity. When determining the tentacles' CMB, the tentacles use your caster level as their base attack bonus and receive a +4 bonus due to their Strength and a +1 size bonus. Roll only once for the entire spell effect each round and apply the result to all creatures in the area of effect.

If the tentacles succeed in grappling a foe, that foe takes 1d6+4 points of damage and gains the grappled condition. Grappled opponents cannot move without first breaking the grapple. All other movement is prohibited unless the creature breaks the grapple first. The black tentacles spell receives a +5 bonus on grapple checks made against opponents it is already grappling, but cannot move foes or pin foes. Each round that black tentacles succeeds on a grapple check, it deals an additional 1d6+4 points of damage. The CMD of black tentacles, for the purposes of escaping the grapple, is equal to 10 + its CMB.

The tentacles created by this spell cannot be damaged, but they can be dispelled as normal. The entire area of effect is considered difficult terrain while the tentacles last.

The first question: Are the tentacles a creature or an object? If it's an object, then the burst deals damage to it, but the tentacles can't take damage, and we're done.

If it's a creature, what kind of fort save does it have? If it fails that, then you get the new save with a bonus or grapple roll with a bonus.

[Quandary]

It's not an object or a creature, it's just a spell effect. It doesn't have any Saves to make, or HPs to destroy...
Other than trying to escape from it normally, about the only thing to affect it is a Dispel check or equivalent.
For some characters, the best way to escape from Black Tentacles may just be using Total Defense,
which adds +4 dodge bonus (or +6 with 3 ranks in Acrobatics) which is a bonus type that affects CMD.

That said, if not held to strict RAW, I would allow the free "Break Grapple" check with the given luck bonus.
(the spell should really allow the same bonus for use with Escape Artist checks, but again, that's not RAW)