Common ropers are merely the most often encountered. Their race is bizarrely diverse, perhaps due to the mysterious link to mimics in their origin.
Some ropers are far more mutable than their cousins. These ropers, sometimes called molting stranglers, shed their external rocky carapace every few months, sloughing it off like crusted dead skin. Each time their skin sheds, the ropers’ form becomes less permanent and more changeable. They gain the ability to assume other forms, taking on diverse shapes, even mimicking the appearance of other creatures (in the same manner as a mimic). Additionally, their shed skin sometimes clings to a miserable semblance of life, acting as a simulacrum of the roper for a short time before dying horribly. The molting stranglers often use these pathetic shed skins to lure enemies into traps, hastening the end of their sick half-life.
Common ropers are composed of a rock-like substance similar to granite or marble, but some varieties are composed of different stone. One of the more dangerous mutations is made of a stone similar to basalt. These basalt ropers, also called vulkards, lack their cousins’ vulnerability to fire, and instead are immune to it. Additionally, these ropers feed on fire, growing stronger and healthier when exposed to it; any attack against a vulkard that deals fire damage heals 1 point of damage for every 4 points of fire damage it would otherwise deal. A vulkard gets no saving throw against attacks that deal fire damage.
Far more insidious and dangerous breeds of ropers exist. Sigil crags, a strange and timeless race of ropers, manifest bizarre and powerful runes of crystal on their rocky exteriors. These sigils of power crystallize after a particularly interesting meal, which usually takes days instead of hours, and most often when the prey is a powerful spellcaster. Sigil crags often munch down the caster’s hands first, leaving him incapable of casting spells with somatic components, and then explore his secrets during a lengthy feast. The secrets coughed up in the crushing embrace of a sigil crag as the hideous thing slowly masticates a caster’s limbs are unthinkably powerful. Each sigil covering a sigil crag’s hide allows it to cast a symbol spell of the GM’s choosing once per day. Most sigil crags are only fortunate enough to enjoy a few sigil-worthy meals in the course of a lifetime, but particularly old and powerful ones are encrusted nearly completely in these dread runes. Sigil crags are CR 13.
A particularly gruesome breed of roper is the dreaded shardstriker. The strands of a shardstriker are jagged, stone-like threads which rend opponents to shreds even as they ensnare them. These brutish degenerates of the roper race are far less philosophical than the others, but they make up for this shortcoming with a healthy dose of sheer viciousness. These demented ropers slice victims to gory bits, often shredding them with all six of their strands. A strand attack by a shardstriker deals 1d8+4 slashing damage as well as dragging the foe. If a shardstriker hits a single foe with more than one strand, it also rends him for an additional 2d6+6 slashing damage. Shardstrikers are CR 13.

Dungeon Denizens Revisited. Copyright 2009, Paizo Publishing, LLC Authors Clinton Boomer, Jason Bulmahn, Joshua J. Frost, Nicolas Logue, Robert McCreary, Jason Nelson, Richard Pett, Sean K Reynolds, James L. Sutter, and Greg A. Vaughan.