Help Iding this critter

[youdunnome]

Picked up some coral last night and while dipping I noticed these on a plug holing Pavona(potato chip). All my other corals came from the same tank,however, just the Pavona plug had these on it. I dipped in revive and around the 10-15 min mark all the unknown pest succumbed to the dip. I've never seen anything like this. I'm leaning towards a pod of some kind. I inspected all corals and plugs and didn't see any eggs either.

Should note the critters moved quick and kinda just glider never saw the body move.

 

[ISpeakForTheSeas]

If they have legs underneath, they're a beneficial isopod, possibly Cassidinidea ovalis; if they don't have legs, they're a harmful flatworm.