The 
Sculk Jaw is a trap block from the Deeper and Darker mod that hides in the Sculk Stone of the Otherside. Stepping on one will make it snap open and bite you, dealing damage and stealing some of your experience, and it’ll keep chewing for as long as you’re stuck inside it.
It’s one of the more annoying hazards you’ll meet in the Deeplands, but there’s an upside, as every point of experience it takes is stored inside the block. Breaking it gives all of that back, and with Silk Touch you’re able to take the Jaw home and use it as a trap of your own.
Obtaining
Sculk Jaws generate in small clusters inside the Sculk Stone of the Deeplands, the Echoing Forest and the Blooming Caverns, and they can turn up in the Sculk Grime at the bottom of those biomes too. They don’t generate in the Overcast Columns, since there’s no Sculk Stone there to replace.
A lot of them are buried inside the rock, so you’ll often come across one while tunneling rather than out on the open floor. They’re quickest to break with a hoe, and you’ll only get the block itself with a Silk Touch tool, as breaking one normally drops nothing but the experience stored inside it.
How It Works
When anything alive steps onto a Sculk Jaw, it opens up and you drop into it, taking 3 damage from the bite. While you’re inside, it’ll keep biting you for about two seconds, and each bite also takes 4 points of experience if you’re a player, so a bad landing can cost you a few chunks of a level.
After that it closes up again, ready to bite whatever steps on it next, so you’ll want to climb out quickly rather than wait inside. The bite counts as its own kind of damage, which is why the death message says you were devoured rather than killed by a block.
Crouching stops a Sculk Jaw from opening when you walk onto it, so sneaking across a suspicious patch of Sculk Stone will keep you safe. Players in Creative are never bitten either, which makes them easy to move around while you’re building.
Sculk mobs like the Shattered and Stalkers won’t set one off by walking over it, as the Jaws leave other Sculk creatures alone. Any other mob will trigger them though, including Zombies and Skeletons you’ve led into the Otherside, which is what makes them useful as a trap.
Uses
The experience a Sculk Jaw steals isn’t lost, as it’s kept in the block, and breaking the Jaw drops every point of it as orbs. If you’ve been bitten a few times, it’s worth breaking the Jaw before you move on, and you’ll get the experience back whether or not you’re using Silk Touch.
Once you’ve collected one with Silk Touch, a Sculk Jaw works just as well wherever you place it, so it makes a simple mob trap at the entrance to a base or along a mob farm’s floor. It won’t take experience from mobs, only from players, but the 3 damage per bite adds up quickly on anything that falls into it.
It’s worth thinking about where you put them though, as they’ll bite you just as happily as a mob if you forget one is there. Keeping them in spots you won’t walk through yourself, or crouching whenever you cross them, saves you from losing your own experience.
FAQ
A Sculk Jaw opens and bites anything that steps on it, dealing 3 damage and taking 4 points of experience from players with each bite. It generates in the Sculk Stone of the Deeplands, Echoing Forest and Blooming Caverns, and crouching will stop it from biting you.
Break the Sculk Jaw that bit you, as it stores all of the experience it has taken and drops it as orbs when it’s mined. This works with any tool, so you don’t need Silk Touch to get the experience back, only to keep the block.
Mine it with a Silk Touch tool, ideally a hoe as that’s the fastest, and it’ll drop as a block you can place anywhere. Without Silk Touch it drops nothing, apart from any experience it was holding.
