Rock Mite

Rock mites are smallish, sturdy, heavily-armored... things.DFRPG: Monsters 1, p.47 They appear to be made of solid rock. Despite their semi-humanoid appearance, they are said to act more like ants (or termites) than sapient beings. They eat rocks, and if legend is to be believed, also excrete metals. Their mouths are a glowing inferno of magma, which they can use (somewhat clumsily) to defend themselves, grabbing onto intruders with their stubby, powerful hands and biting. 
== Incidents and Avoidance ==
Most incidents with rock mites are the result of delvers accidentally entering their nests while prospecting. Rock mites only really care about two things -- raw minerals, and personal space.
== Defying Categorization ==
Rock mites aren't affected by Animal nor Mind Control spells -- no one's really sure what they are. Some people believe they're "drones" of some kind of eusocial hive, like ants or termites -- there are tales of a "warrior" caste that are more dangerous and territorial. Some folks even think they serve some unknown "rock man" civilization, deep in the mountains.Dungeon Fantasy: Monsters 1, p.25 
There are a few more interesting theories -- perhaps they are some sort of elemental homunculi species that managed to reproduce (albeit that's just as inexplicable), they may even be related to gargoyles, if only vaguely.Pyramid #3/118: Dungeon Trips, "Eidetic Memory: Istvan's Hole", p.31
== Sidebar: Rock Mite Lairs ==
Rock mites can survive just about anywhere there's rocks to consume, from the fiery depths of the earth to the scarce atmosphere of mountain peaks, even underwater. Some rumors say that entire mines of rock mites are kept by intelligent monsters who feed the beasts minerals and collect their metallic poops. Of course, it would take a lot of corralling to keep rock mites together -- they're particularly ornery, and will chew their way out of most barriers.
== Anatomy ==
Naturalists on the cutting edge of the fantasy world have found that rock mite hide is a series of overlapping cobbles, with only some small amount of magical "fascia" keeping the creature together. This mana-based inner layer explains the fragility that hides beneath their tough exteriors -- if one of their limbs are crippled, it simply falls right off!
Furthermore, rock mites have no "necks" -- their entire "head" area is a continuation from their torso, giving them a roughly "paraboloid" shape. They lack any sort of "weak spot", save for a vulnerability to earth-magics.
== Homebrew Alterations ==
=== More-Mortal Mites ===
If Rock Mites are built a little too tough, maybe change them to regular (living) creatures with higher HP, instead of making them Homogenous. Allow their DR to vary wildly -- perhaps the rock mites ruining grandma's cellar aren't as tough as the ones digging through the Death Peak of Danger Mountain.
=== Cool Your Jets and Onyxs ===
A rock mite's proportionally huge, glowing mouth would make sense as a weak spot if anyone can risk getting their weapon bitten (try casting Resist Fire). Likewise, if the creatures rely on a boiling-hot body to survive, they'd probably be knocked unconscious or destroyed if they're hit in the mouth with Water Jet!
== Trivia ==
* According to Pyramid 3/77: Combat, "It's A Threat!", Rock Mites have an Offensive Rating of a mere 13 but a Protective Rating of 53, with a total Combat Effectiveness Rating of 66. It has one of the lowest Offensive Ratings, likely due to its clumsy, range-limited attack.
* In Pyramid 3/99: Death and Beyond, "What Doesn't Kill Me Makes Me Stronger", a Rock Mite's "Kill Points" are about 47.
* Murphy's Rules?: Due to a possible oversight in Pyramid 3/104: Dungeon Fantasy Roleplaying Game, p.30, "Eidetic Memory: Heroic Background Generator" (what a mouthful!) it's possible to roll up a character who was raised by Rock Mites.
* In their simplified The Fantasy Trip adaptation, Rock Mites are simply considered immune to fire damage, and oddly enough, have a vulnerability to blunt weapons.
** Additionally, this entry mentions that if a Rock Mite's prey is immune to their fiery maw, they simply claw at them instead.
== References ==
* Dungeon Fantasy Monsters 1, p.25
* DFRPG: Monsters 1, p.47