This large horned creature has a metallic shell that clicks and clacks as it skitters towards you.
Nailhead, Iron (CR 3)
N Small vermin
Init +1; Senses darkvision 60 ft.; Perception +0
AC 16, touch 12, flat-footed 15 (+1 Dex, +4 natural, +1 size)
hp 30 (4d8+12)
Fort +7, Ref +2, Will +1
Speed 30 ft., burrow 10 ft.
Melee head butt +7 (2d6+4)
Special Attacks digestive acid
Str 16, Dex 12, Con 16, Int —, Wis 10, Cha 9
Base Atk +3; CMB +5; CMD 16 (24 vs. trip)
Skills Climb +8
Burrow (10 feet) You have a Burrow speed.
Damage Reduction (5/adamantine) You have Damage Reduction against all except Adamantine attacks.
Darkvision (60 feet) You can see in the dark (black and white only).
Digestive Acid (3/day) (Ex) A nailhead can spit a glob of its highly corrosive digestive acid up to 20 feet as a standard action, usable every 1d4+1 rounds. This is a ranged touch attack with no range increment. Creatures struck by this attack take no damage, but the acid deals 1d6 points of acid damage per round to any metallic armor worn by the target. If desired, the target can use a full-round action to wipe off the acid to prevent additional damage.
If the acid reduces the armour’s hit points to zero, it disintegrates into a foul smelling ooze. This ooze serves as a food source for the nailhead, nourishing it and allowing it to build upon its carapace.
Unwavering (Ex) A nailhead is both thick skinned and thick skulled, granting it full immunity to nonlethal damage.
Organization solitary, pair, gang (3–6), or hive (10–100 and 1 queen)
Nailheads are small anthropods that reside in mines and other caves that are rich in ore. In their natural form, nailheads have soft limbless bodies, resembling oversized silk worms, and pose no threat to adventurers. However, if allowed near any sort of metal, nailheads are capable of ingesting the material and excreting it as metallic silk. The silk has the same qualities of whatever metal was ingested and can be spun into webs and other constructs. Nailheads specifically use this material to craft durable exoskeletons for themselves, complete with their eponymous large spiked horns. Nailheads become aggressive and territorial when armoured in such a manner and can pose a major threat to unprepared adventurers – especially if they’ve been feasting on particularly remarkable ore.