Sources
CR
Type
Size
Alignment
Movement

Oblex Spawn

Tiny Ooze, Lawful Evil

Armor Class 13
Hit Points 18 (4d4 + 8)
Speed 20 ft.
STR
8
-1
DEX
16
+3
CON
15
+2
INT
14
+2
WIS
11
+0
CHA
10
+0
Saving Throws INT +4, CHA +2
Condition Immunities Blinded, Charmed, Deafened, Exhaustion, Prone
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 12
Languages
Challenge 1/4 (50 XP)

Traits

Amorphous. The oblex can move through a space as narrow as 1 inch wide without squeezing.

Aversion to Fire. If the oblex takes fire damage, it has disadvantage on attack rolls and ability checks until the end of its next turn.

Unusual Nature. The oblex doesn't require sleep.

Actions

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:5 (1d4 + 3) bludgeoning damage plus 2 (1d4) psychic damage.

Lore

Mind flayers unleash all manner of foul experiments upon the planes with little thought for the consequences. Here, though, I suspect another influence: Juiblex.