Ankheg

The Ankheg was a huge insect looking monster with many slender limbs and large antenna. It burrowed underground and hunted from bellow.

Enivoroment
Living in warm climates the Ankheg dwelt in partially collapsed burrows usually around 40 feet under ground. The Ankheg hunted in forests or grasslands where prey would wander in to its trap. And if a area becomes to barren the Ankheg moves on to another more lucrative areas. Ankheg tunnels where some times filled with the remains of victims, eggs or chitins. There tunnels would some times be around 60 to 150 feet long and 5 feet high. Hollow tunnel ends where used for lair purposes like sleeping or hibernation.

Combat
The Ankheg was a ambush predator that waited around 5-10 feet underground for a pray to wonder in position, the attack was quick as the pray was crushed and grinned in its mandibles and assaulted with acidic digestive enzymes. If a foe proved to difficult it could also squirt acid to take it down. If several Ankhegs are attacking a group they would try to attack different targets. If a prey was attacked by more then one Ankheg they would just tug-of-war the unfortunate prey.

Social structure
In a general area could have a lone, pair or a cluster of Ankhegs.

Diet
Gaining nutrients from the ground the Ankheg also had to hunt fresh meat to sustain it self. It could also eat decaying meat.

Physiology
Having darkvision and tremorsense for 60ft and strong chitins. The "attack" acid was part of the digestive system for the creature so it couldn't digest food for 6 hours after after a discharge. Ankhegs that lived in colder areas hibernated during winter, during this time it took nutrients from its shell and its antennae where still active.

Life cycle
Ankhegs mated in autumn where the fertilised female would kill the male to lay 6-12 eggs inside him. Usually a high number of eggs survive and hatch within a couple of ten days and start to feed. An Ankheg broodling would not hunt and where hidden and a parent would bring it sustenance. After a year the young would be able too fend for them self. Around year two the young Ankheg would shed its chitin before winter, it took it little less then a ten day to complete the processes and get a new shell. During this time the youngling was slower and more vulnerable to defend it self it secreted a fluid that smell like fruit rot. This defence could backfire as some would seek out the smell.

Effect
Ankhegs could prove to be useful for a farmer that could stay alive, its tunnels could bring in water and its excrement had enriching minerals.

Baldur's Gate (video game)
In the Baldur's Gate video game, Ankhegs are a fightable monster. Once killed players can collect the Ankheg shells. Each shell weighs 100 lbs.

Taerom the Blacksmith, in Beregost forges armour from the shells. It takes three days to make. The armour is very nearly as effective as full plate mail, but weighs considerably less and can be worn by classes that usually couldn't wear such heavy armor. Taerom claims to sell ankheg armour to rich nobles for 20,000 GP. If you provide the shell, he will charge just 4000 for a set of completed armour.