I was thinking it was some sort of slug also. Because some parts do not look to be fully connected to the plant. they look like there fighteing over which slug can suck life from the plant. And the ants are eating them, or cleaning them. Then it would be a symbiotic relationship.

I dont see any dead slug looking things. So thats my guess.

Do those slugs or bubbles of ooze move? can u pick at least one off and look at the underside of it?