This creature didn't get a lot of responses on the GITP forums, so I'm hoping I'll have better luck here.
Hit Die: 20d10+30 (140 hp)
Speed: 20 ft. (4 squares)
Armor Class: 22 (-1 size, -2 Dex, +15 natural), touch 7, flat footed 22
Base attack/Grapple: +15/+25
Attack: Claw +20 melee (2d8+9 damage)
Full Attack: 3 Claws +20 melee (2d8+9 damage)
Space/Reach: 10 ft./5 ft.
Special Attacks: Petrifying touch, berserk
Special Qualities: Damage reduction 20/adamantine, Immunity to magic, darkvision 60 ft., lowlight vision, construct traits, immunity to cold
Saves: Fort +6, Ref +4, Will +6
Abilities: Str 29, Dex 7, Con -, Int -, Wis 10, Cha 1
Challenge Rating: 12
Alignment: Always neutral
Advancement: 21-40 (Huge); 41-60 HD (Gargantuan)
Level Adjustment: -----
A massive, shambling mound of remnants comes walking forward. The bones this creature is composed of seem almost rock-like in appearance. It seems to be made of the fossils of various creatures, with multiple heads and many, many limbs.
Fossil Golems are similar to bone golems, except the bones have become hardened with the fossilization process. Fossil Golems are generally used by those excavating areas deep in the Underdark. Since fossils are generally common as workers go deeper and deeper underground, they may higher powerful spellcasters to create powerful construct guardians out of the supplies available.
Fossil Golems are animated by an earth elemental power source. Fossil Golems are considered very dangerous, because they have a petrifying touch that induces the fossilization process, which acts similarly to a flesh to stone spell.
Fossil Golems enter combat when commanded to. They try to attack with their petrifying touch first, and try to mop up the rest with their claw attacks.
Immunity to Magic (Ex): A fossil golem is immune to any spell or spell-like ability that allows spell resistance. In addition, certain spells and effects function differently against the creature, as noted below.
A transmute rock to mud spell slows a stone golem (as the slow spell) for 1d6 rounds, with no saving throw, while transmute mud to rock heals half of its lost hit points. A stone to flesh spell does not actually change the golem’s structure but negates its damage reduction and immunity to magic for 1 full round.
Berserk (Ex): When a fossil golem enters combat, there is a cumulative 1% chance each round that its elemental spirit breaks free and the golem goes berserk. The uncontrolled golem goes on a rampage, attacking the nearest living creature or smashing some object smaller than itself if no creature is within reach, then moving on to spread more destruction. The golem’s creator, if within 60 feet, can try to regain control by speaking firmly and persuasively to the golem, which requires a DC 19 Charisma check. It takes 1 minute of inactivity by the golem to reset the golem’s berserk chance to 0%.
Petrifying Touch (Sp): At will, a Fossil Golem can perform a touch attack to magically morph an enemy into stone. This is similar to the flesh to stone spell, and has the same effects. Caster Level 10th.
Fossil Golems are constructed out of various bones and rocks, the remnants of creatures long dead. The exact body shape varies, but they usually have two-four arms (the example above uses three), skull fragments from three different creatures, and is usually a quadruped. The construction needs at least eight fossilized corpses. It costs 8,000 gp to excavate and prepare the fossils. Special unguents and bindings worth 1,000 gp are required.
Assembling the body requires a DC 18 Craft (stonemasonry) check.
Caster level 13th;Craft Construct, antimagic field, geas/quest, flesh to stone, limited wish animate dead; Price 21,000 gp; Cost 10,500 gp+420 XP.