Jade Oozeling
Source: Pet Battle. Jade Oozelings glow in the dark, making them a welcome sight to workers in pitch-black mineshafts. Magic type. There were no Jade Oozelings in the cave when I arrived at the cave. After running through the whole cave killing everything, including the critters, 2 of them spawned.
The Jade Oozeling is a wild pet found at Skulk Rock in the Hinterlands, and spawning it requires killing the Level 1 Maggot critters scattered inside and outside the cave rather than the Jade Oozes or Green Sludges.
Guide awaiting review
Travel to Skulk Rock
Head to Skulk Rock in the Hinterlands, where Jade Oozelings can be found both inside the cave and just outside near the cave mouth.
Kill all Maggot critters
Circle the inside and outside of the cave killing every Level 1 Maggot critter you find — killing the Jade Oozes and Green Sludge mobs does not trigger Jade Oozeling spawns, but eliminating the maggots does, with Jade Oozelings appearing shortly after.
Be considerate of questing players
There are quests in this zone that require killing Jade Oozes and the Direglob, so if a level-appropriate player is actively questing through the cave, avoid mass-clearing the mobs they need.