The Shriek Worm is a hostile mob from the Deeper and Darker mod that bursts out of the ground when you step on 
Infested Sculk in the Otherside. It’s a huge sculk worm that rises up out of the floor and attacks anyone close by, but it can’t move from the spot it came out of, so it works more like a trap than a mob that hunts you down.
It has 100 health, which is 50 hearts, and it doesn’t drop anything when it dies, so there’s little reason to fight one unless you need it for an advancement. Most of the time, the best thing to do is to get out of its reach and carry on, and know what to look out for next time.
Spawning
Shriek Worms don’t spawn on their own. Instead, they’re hidden under Infested Sculk, a block that looks exactly like normal 
Sculk, and the worm only comes out when a player steps on it. The block turns back into plain Sculk and knocks you back a little, then the worm starts to rise up out of the ground where it was.
Infested Sculk generates in small patches inside the Sculk Stone of the Deeplands, the Echoing Forest and the Blooming Caverns. Since it can’t be told apart from normal Sculk by looking at it, you’ll usually find out where one is by walking over it, though mining your way through caves will turn up a few as well.
Breaking Infested Sculk without Silk Touch releases a Sculk Leech instead of a worm, and you won’t get the block back. With a Silk Touch tool, it drops as a normal Sculk block and nothing comes out, which makes Silk Touch a safe way to clear a patch you’ve found.
Behavior
It takes the Shriek Worm about 4 seconds to rise up out of the ground, and it can’t be hurt while it’s doing this. Once it’s out, it will attack the closest player it can see, hitting anyone within about 3 blocks of it for 7 damage on Normal roughly once a second.
Because it can’t move, getting more than 3 blocks away from it is all you’ll need to do to be safe. It doesn’t take any knockback either, so you won’t be able to push it back to make room, and it’s easy to get stuck trading hits with it if you stay close.
Burrowing Back Down
If a Shriek Worm goes a full minute without attacking anyone, it burrows back down into the ground, and it can’t be hurt while it does this either. Once it’s gone, it leaves behind a new Infested Sculk block, so the same spot will release another worm the next time someone steps on it.
That means walking away from one doesn’t get rid of it for good, it only resets the trap. If you’d like to clear a spot you use often, you’ll either need to kill the worm or break the Infested Sculk it leaves behind with a Silk Touch tool.
Drops
The Shriek Worm doesn’t have any item drops at all, so killing one won’t get you anything apart from some experience. It’s one of the mobs you’ll need for the Sculk Slayer advancement, though, along with the Stalker, the Shattered and the Warden.
If you do want to kill one, a Bow is the safest choice, as it can’t reach you from range and can’t come after you. Weapons with Sculk Smite will deal extra damage to it too, which helps a lot with 100 health to get through.
FAQ
Step on Infested Sculk, which looks just like normal Sculk and generates in small patches in the Deeplands, Echoing Forest and Blooming Caverns. The block turns into Sculk and the worm rises up out of the ground over about 4 seconds.
It doesn’t drop any items, only some experience, so most players walk away from it rather than fight. You’ll still need to kill one for the Sculk Slayer advancement, which asks for most of the sculk mobs in the mod.
It can’t move at all, so it only attacks players within about 3 blocks of the spot it came out of. Stepping out of its reach is enough to be safe, and it will burrow back down after a minute without attacking anyone.
Break it with a Silk Touch tool and it drops as normal Sculk with nothing inside, which is the safest way to clear it. Breaking it without Silk Touch lets a Sculk Leech out instead, while stepping on it releases a Shriek Worm.
