Per 
Item #: SCP-3918
Object Class: Euclid
Special Containment Procedures: -Still deciding on this. Possible use of SRAs to keep the 'hot-spot' from growing outside mammoth cave national park-
Description: SCP-3918 is a parallel universe accessed through cave-systems in various sections of the world (See addendum 3918.1 for more information on current access points). SCP 3918 is a mass of interconnected caverns, ranging from inch-wide crevices to chambers large enough to fly a C-130 Hercules comfortably. Notably 3918 super-caverns are separated in layers, roughly connected by massive (10-mile radius at smallest) sinkholes. These sinkholes constantly emit SCP-3918-1 in varying intervals. Staff have compared the rhythm to breathing.
Through anomalous and currently unknown means, SCP-3918 receives a constant supply of dead earth organisms. Testing has revealed that terminating a subject will deposit a cadaver in a near-exact spot within the corresponding shell. Archeological evidence has shown the oldest organism within SCP 3918 is Grypania spiralis. Suggesting the anomaly has been active since 1870 million years ago.
SCP-3918 is host to a unique ecosystem dominated primarily by the Opisthokont superclade, with eubacterial and protist life serving as a close second.
SCP-3918-1 is an anomalous, microscopic fungus bearing genetic similarities to Ophiocordycipitaceae. If a sufficient amount of SCP-3918-1 is inhaled by an individual, they will slowly become an instance of SCP-3918-2.
So im thinking for SCP-3918-2. Infected individuals essentially become human-fungi hybrids. The fungus taking over and replacing much of their body.
It tends to go in stages. The first stage essentially has the fungus replacing destroyed or damaged cells. Skin quickly becomes a tough keratin-chitin lattice, and muscles are similarly reinforced after use. In addition severed appendages can heal and re-attach without any need for medical supplies. Cell division and reproduction occurs at phenomenal rates, although tissue quality will degrade over time. Mentally the subject is quite fine
Middle-stage is when they become actively infectious to others. By this point mycelia has reached the brain and begins to integrate with host nervous system. Infected individuals will become highly aggresive and belligerent to non-infected, with focus more on forcibly infecting than harming. Senses are noted to be improved in most cases. By this point the fungus has fully integrated with muscle and skin-tissue, giving infected individuals superhuman strength and durability. Damaged skin now reflexively grows chitin-laced fungal plates similar to Polypore fungi. Subject now begins to spread spores through exhalation.
Late-Stage: By now subject is from anywhere from 70-90% fungal tissue by mass. Infected individuals still show intelligence, but seemingly refuse to communicate to non-infected. Subjects notably acquire a voracious appetite, constantly consuming to increase fungal mass. Subjects have been demonstrated to augment this process through skin-hyphae extensions. Muscle hypertrophy is noted in all cases. Extreme laryngopharyngeal reflux is developed, giving SCP-3918-2 corrosive saliva. Some instances have been noted to produce acids stronger than HCL in response to different envrionments (see incident log).
Mutations in the endocrine system seemingly allow SCP-3918-2 to calcify sections of its body that frequent damage. Combined with reactive regeneration this makes SCP-3918-2 extremely hard to terminate through small-arms. Muscle-growth is noted around the sub-mandibular duct, allowing infected individuals to spit spore-laden saliva at non-infected.
The latest stage subjects have been shown to carry significant amounts of volatile gases and substances, such as hydrogen sulfide and methane. Upon significant bodily damage, these volatiles will ignite. Effectively terminating the SCP-3918-2 instance, but at the cost of massive spore dispersal. Subjects have noted bone dysplasia and skeletal elephantiasis. Termination by small-arms now practically impossible.
Addenum 3918.1: -Currently looking for caves, but ideas so far are: Mammoth-Cave system, The really-deep Georgian one, Chauvet-Pont-d'Arc Cave (explains all the metal doors and climate control)-
Addenum 3918.2:
