I call it a "lurk" (plural form: lurks, or a puddle/field of lurks)
Usually they are on the ground and kinda look like flowing seaweed but in the air. It doesn't do much other than flow around. And it doesn't make a lot of noise.
However the second there is someone nearby immediately that's when it does something, usually by becoming solid-like and begins to grab its victim and it sinks their victim into the ground. Usually after they get it's victim immediately it will dissolve away or become a flat surface, making it impossible to get through unless your strong enough.
The victim will then be transported to this strange void-like place, and there is low gravity in that place. This will make the individual float around. However that does not mean the victim is safe from harm. At first nothing happens but the truth is the seaweed thing is actually reading the person's mind and looking through their memories and everything about them. After a few minutes suddenly the seaweed-like things will begin to create these illusions and fake-beings in the individual's mind, they will begin to try talk to the individual but sometimes the lurk makes mistakes and might miss a few features (dyed hair, jewelry, scars, accessories)
If the individual is smart enough they can easily dismiss the first ones and shoo them away. However it gets harder as the lurk begins to read more and even create replicas. They will turn into the individual's loved ones and say hurtful things to them to try to get them off guard. Even replay scenes from the individual's memories. After all the lurk wants to make their victim as vulnerable as possible.
Then if all of that doesn't work and the individual begins to try to fight back the lurk will become into the individual's most desired/closest person or a dead relative they miss dearly. The lurk will pretend to be that person and say things to get into the victim's head, or even begin to cry and beg if the victim tries to ignore them. They will say things to make the victim more vulnerable, and even make a lot of good points depending on how the victim thinks. Then finally if the victim gives in they kill the victim and the victim begins to dissolve into nothing. Unless they are strong enough they destroy the replica, however since the lurk took longer to make that replica the replica can actually bleed and get injured, the replica will beg and cry, telling them things such as "why are you doing this to me?" "Please stop!" And etc...
The lurk is most weak against fire or any heat-based attacks. No it is not possible to bring out the replicas or clones the lurk creates because if the clone or replica is 10 feet away from the lurk it will immediately dissolve or melt in seconds.
It is possible to escape the lurk if the individual is mentally strong enough.