Does an earth elemental give a bonus or benefit to digging?

Question

Does a summoned small Earth Elemental give any bonus or benefit to digging through stone?

An example case:

Bob the L5 Wizard wants to hide a treasure chest weighing 50 pounds in the lowest level of his dungeon, and hide it fairly well, so he summons a small Earth Elemental. The Earth Elemental grabs the chest and spends 5 rounds (at 20 feet per round) using Earth Glide to drag the chest beneath the rock.
At the end of the five rounds the chest is buried without trace.

Tim the L3 Wizard comes by years later with a dozen human friends. All the friends have picks and shovels, and each has a STR of 16, the same as a small earth elemental. Tim could stand on roughly the same spot and cast Summon Monster II over and over while the small earth elemental "Earth Glides" around, searching for the buried chest. The elemental eventually pinpoints the chest's location with Tremorsense, but at 90' below the floor surface the level 3 Summon Monster II spell ends before the elemental can reach the chest.

If the Earth Elemental tried to "dig up" the rock and stone, does he get a bonus? Or does he dig the same as the humans?

Answer 1

An earth elemental digs no faster than any other creature

The only Pathfinder rules for digging that I'm aware of are part of the mundane hazard cave-ins and collapses, which says...

In 1 minute, using only her hands, a character can clear rocks and debris equal to five times her heavy load limit. The amount of loose stone that fills a 5-foot-by-5-foot area weighs 1 ton (2,000 pounds). Armed with an appropriate tool, such as a pick, crowbar, or shovel, a digger can clear loose stone twice as quickly as by hand.

(Extrapolated, a creature without tools can clear rocks and debris equal to its heavy load in 2 rounds and with tools its heavy load in 1 round. Unless, of course, your strict GM rules that a creature must labor for 1 min. to clear any debris.)

So, if the Int 4 earth elemental doesn't know how to (or can't or refuses to on religious (ahem) grounds) use a shovel, the Small earth elemental's a worse digger than the celestial pony that can be summoned using summon monster I. That is, the biped Str 16 Small earth elemental's heavy load is only 172.5 lbs., while the quadruped Str 13 Medium pony's heavy load is 225 lbs.

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The example's issues

A Small earth elemental summoned by the typical level 5 wizard using summon monster II can take 5 turns to double move each turn to travel 200 ft. into the earth, but probably travels only 180 ft. into the earth after it takes a move action to attend the chest. A Small earth elemental summoned by the typical level 3 wizard using summon monster II can take 3 turns to double move each turn to travel 120 ft. into the earth, and, using tremorsense, finds the chest if the chest's within 60 ft. of the elemental, but the elemental disappears before it can return to the surface to tell the summoner what it's found, the duration of the level 3 wizard's summon monster II expiring after 3 rounds.

Were the level 5 wizard's earth elemental to have buried the chest only 100 ft. underground, the level 3 wizard's earth elemental still couldn't've retrieved the chest, but the elemental could've informed the wizard of the chest's location. (That is, the level 3 wizard's elemental takes a double move to descend 40 ft. and finds the chest as the chest's within 60 ft., then takes a double move to ascend to the surface and, in Terran, tells the wizard where the chest is, 1 round remaining on the spell summon monster II's duration.)

Keep in mind, too, that typical burrowing leaves no tunnel (therefore doubly true for the special ability earth glide), so there's no way for the earth elemental to create using its special abilities a path for the summoner to the chest.

Answer 2

The only bonus Earth Elementals get to digging is their innate Knowledge (Dungeoneering); that skill doesn't increase the speed, but increases the safety (say, if Bob directed the earth elemental to hide the chest in a pocket of toxic gas). Other than that, it can move mass around as much as any other creature of its size and strength.

Granted, you're not going to see too many Small creatures with a Strength of 16...

Answer 3

Paizo Source

Earth Glide (Ex) A burrowing earth elemental can pass through stone, dirt, or almost any other sort of earth except metal as easily as a fish swims through water. If protected against fire damage, it can even glide through lava. Its burrowing leaves behind no tunnel or hole, nor does it create any ripple or other sign of its presence. A move earth spell cast on an area containing a burrowing earth elemental flings the elemental back 30 feet, stunning the creature for 1 round unless it succeeds on a DC 15 Fortitude save.

If we acknowledge that metaphorical passages are actually rules - we can extrapolate from this. I'd take 'As a fish swims through water.' as a base. And 'any other sort of earth except metal' - is interesting too. First of all - chest is made of wood and perhaps metals - so that is not falling under earth elemental's domain of special quailities. Next - nothing is said about earth elemental carrying objects so that can be approached as 'if it is not allowed then it's denied'. Moreover, the passage about 'fish' illustrates it's movement through the earth - if we stick to the fish something that can't pass water freely - fish would not be able to move - it will be constrained.

What this illustrates to us is earth elemental's ability to pass through the earth is tightly coupled with the fact it's body is made from earth. And only that special body has some special power to dive through other types of earth and stone.