This creature looks like a crystalline caterpillar.
Speed 30 ft., burrow 20 ft.
Str 20, Dex 12, Con 18, Int 4, Wis 13, Cha 11
Three times per day, as a standard action, a caterprism can spew forth a crystalline silk-like substance in a cone to a range of 20 feet. The substance instantly solidifies to a rock-like hardness, forming needlesharp spears of crystal that impale those in the area and deal 3d6 points of piercing damage. A DC 17 Reflex save halves the damage. The save DC is Constitution-based.
The mandibles of a caterprism are so sharp that they can bite through nearly anything. The bite attack of a caterprism is treated like a touch attack; i.e., it ignores any armor bonus. Further, the bite of a caterprism is considered to have the vorpal special quality, and on a successful critical hit with its bite attack, the caterprism severs the head of its opponent.