Blind Platemantis

Thagrul and Doukhun managed to sneak into mines of the Diamond Fortress. They'd managed to swipe the key while their boss wasn't looking. They had no intent on actually working, but Thagrul and Doukhun wanted to prepare a prank for the next day's workers. Thargrul had found small rocks that made loud noises when stepped on. Doukhun had come up with the idea to spook their coworkers. 
"Are you sure it's safe to be here without the guard working?" Thagrul asked.
"Of course, nothin' ever comes through here. We'll be fine."
They found their way through the tunnels to one of the equipment rooms. Pickaxes and helmets lined the walls. Taking one of the pouches of spark rocks, Doukhun tossed them all over the equipment room floor. A few managed to get out, which Doukhun stepped on the few that escaped.
They cracked with an echo. Thagrul pulled Doukhun away from them.
"What are you doing? Someone will hear us!" he yelled in a hushed tone. 
"Yeah but if we don't pop these ones someone might step on one and ruin the surprise."
Thagrul was starting to get anxious but he knew how hard it was to stop Doukhun from one of his plans. He was acting like a true dwarf, stubborn as any.
"Fine, just be quick about it."
Doukhun stomped on each spark stone. A small flash of light and a crack that echoed, each one making Thagrul flinch. The hair on Thagrul's neck stood on end before he could hear it. He heard the sound of chittering starting to echo from the caves. He tapped Doukhun on the shoulder. 
As Doukhun turned to look, the beast was already charging for them. Its face opened in a seemingly random array of its hard exoskeleton. Two massive claws dragged the beast at its full speed. Doukhun had heard of the beast, but never believe he'd ever meet one. A Blind Platemantis.
Thagrul and Doukhun took off in a sprint. They both tried to take charge of where they were going, but they only ended up getting separated. The Platemantis stopped at the intersection they split. It took off after Thagrul. Doukhun could only hope that Thagrul could figure out how to avoid the beast. He ran for a little while longer until he found a small alcove in the wall. He didn't bother dousing his lantern, the creature didn't see by light anyway.
He'd wish he had a pickaxe to defend himself with. He didn't have evidence that it would work, as he recalled from a kid a blow from a pickaxe to one would only break the pickaxe but those were just stories. There was no way it could stop a pickaxe. 
Doukhun twitched as he heard a shriek coming from deeper in the mine. He immediately recognized it as Thagrul's voice. He was dead.
Doukhun took the chance to sneak past the monster, assuming that it was busy eating Thagrul. He might still manage an escape. All he had to do was take his time and walk quietly. As he crept along he could hear the ripping at flesh and he picked up speed. For a little while the ripping got louder causing Doukhun to slow in fear of being too close. He turned back toward the equipment room. As he started to pass by, he stepped on a spark rock.
He froze, turning his back from the direction he came. The ripping had stopped. Doukhun started to move again when he hadn't heard a noise, trying to distance himself from where he made the noise. He started to turn down a tunnel when he could see the Blind Platemantis. Without making a sound Doukhun clung to the wall, staying as far away from the Platemantis as he could. It crept slowly, clicking its mouth and following the sound. It was looking for him.
Doukhun watched as the Platemantis started to creep toward the door to the equipment room. He had only a moment to pull off his shoe. An idea popped into his head, it was a stupid one, but it might just work out. As the Platemantis crept into the doorway, Doukhun threw his shoe into the equipment room. The clatter of the shoe on equipment cause the Platemantis to lunge, just as the shoe, the helmets, and one pickaxe collided with the spark rocks on the floor.
They sparked so loud that Doukhun had to cover his ears. The Platemantis was thrashing about, slamming into the wall. Doukhun sprinted down the tunnel to escape the Platemantis. He could start to hear it thrashing against the stone walls. He ran as fast as he could, hoping to make it to the mine entrance before it regained it senses. The door was just ahead.
Doukhun halted, his abdomen being squeezed by large plated claws. An eyeless face looked at Doukhun. As he screamed the Blind Platemantis chewed into his face. Doukhun had been foolish. He assumed there had only been one Platemantis.

Basic Information

Anatomy

A large exoskeleton covers every inch of its body, with small fragments to allow for movement. It's head acts as a giant ear with the exoskeleton moving to direct sounds while having a massive jaw meant to tear prey apart. It's front legs act as massive pincers, akin to a Preying Mantis insect. Its four other limbs are sharp, but allows them to bury the legs into stone, giving it the ability to climb on surfaces.

Genetics and Reproduction

Blind Platemantises lay eggs in hidden locations. They will last for several months without fertilization until another Platemantis comes along to fertilize them. Overall, Blind Platemantises have both reproduction organs. They will rarely find another of their species, wandering the ancient caves looking for food.

Growth Rate & Stages

Blind Platemantises are incredibly quick to grow. When they are born they will cannibalize each other until only one remains. The young then forms an inpenatrable cocoon where it starts swelling in size. When they are roughly 3 ft in diameter, they will burst from their cocoon. They will eventually grow to their full size, shedding their armor as they grow and replacing it.

Ecology and Habitats

Underground in large cave networks. While a Blind Platemantis can go to the surface, they suffer from a form of agoraphobia when their echolocation is directed at the sky. Their armor makes them blend into surrounding stone, some armor patterns have been seen to vary depending on the surrounding rock type.

Dietary Needs and Habits

Blind Platemantises are omnivores. While they prefer fresh meat, that is not always available, sometimes for long periods of time.

Additional Information

Uses, Products & Exploitation

Under the right circumstances, the hard armor of the Blind Platemantis can be used as patches for armor.

Perception and Sensory Capabilities

The Blind Platemantis has no vision, but moves and "sees" with sound. It is incredibly sensitive to sounds. It will sometimes click to act for echo-location.