Barnacle

Barnacles are little more than coagulated fel that attach themselves to the surface of objects as part of their natural processes. They are extremely territorial and unerringly hostile to anything that isn't themselves. They consume virtually anything caught and pulled in by its adhesive appendages.

Overview
Barnacles are among the more grotesque manifestations of the fel. They attach to the surface of inanimate objects (though there are exceptions) located in high traffic areas with the intended purpose of catching and consuming prey.

Barnacles grow from a central mass, that often resembles a mouth. This central organism is where the sensory and motor functions originate. Both organic and inorganic matter are broken down and consumed by this mouth. It does this by growing a dense web of root-like tendrils made from coagulated fel energy. This web will spread outward in every direction from the mass, climbing over walls, structures, trees, and everything it can come in contact with. There it secretes a corrosive acid that breaks down the covered object, and allows the barnacle to convert it into food. This in turn fuels its growth which allows it to continue to spread, and thus repeats the process.

When threatened, a barnacle has a number of defenses. First, the barnacle grows subterranean appendages that resemble bladed pseudopods, which act as the first line of defense for the barnacle. The appendages burst from beneath the ground, and begin to attack anything deemed a threat to the barnacle. If whatever is threatening the creature is capable of getting past these, the mouth can vomit up highly corrosive gases which will choke out and kill any living creature that comes too close. Or dissolve any hardened inorganic matter that does likewise. At which point the roots will begin the process of growing over the defeated foes before consuming them.

If an attacker is formidable enough, killing the central mass will trigger a minor earthquake in the surrounding area, as its death throes reverberate through the ground. At which point it the mouth will begin to ooze fel as though it were blood, spilling out into the surrounding area. The tendrils will slowly recede over the course of many days, or even weeks depending on how large the creature had grown.

Reproduction
Barnacles are created when entropic fel coagulates. Felforges are common locations for barnacles, as the concentration of entropic fel for the creation of fiends allows them to thrive. They're also found in the aftermath of demonic battles, spreading and consuming the remains of those who died.

Impact
Barnacles tend to make the areas in which they reside uninhabitable, even for demons. They release toxic gases into the surrounding environment, they drain the life out of everything they touch with their roots. A barnacle will kill and consume virtually anything it comes across or feels threatened by. Whole felforges have fallen to barnacle infestations, requiring specialized teams to go in and uproot them.