The ripper is a former miner and wears the DS1 level 3 suit. They are semi-sentient in the fact that they can grasp
non-remote minig tools and try to beat isaac to death if one of their blades which is a different none arm appendage are cutt off.
If they still have the blade they will succesfully rip Isaac a new one.
The ripper also has enough intelligence to open doors and run to cover if damaged.
(Here comes a storyline idea!) Isaac's first weapon is a plamsa saw found near a dead ripper.
The ripper can only kill if both blades and at least one other limb are dismembered.
I'll upload my concept art to deviantart.
The biomass is a mass of flesh and bone transformed into a scorpion like creature. It's head is a combination of 4 human heads and it has 3 limbs 2 arms used for walking and a third slasher arm as a weapon.
The only way to kill it is dismembering the weapon becuase it can be used as a lever for the Biomass to leap off.
The biomass can look like a pile of limbs and torsos as camouflage.
Not much of an offensive necromorph but stil dangerous it grows out of the corruption much like a cyst but if isaac steps on the corruption the screacher will emmit a shreek that alerts all the necromorphs in the area.