Cleon
Legend
I'm fine with a natural armor. I picture it "oozy" on the inside with a crusty series of plates on the outside. As a result, I'd suggest we note that unlike most oozes, they cannot thin out nearly as small and creep under doors, through holes, etc.
I also think we need an ability that allows them to "lock" with others of their kind to create a long wall. That way, a single ooze cannot be moved, squeezed past, etc. Thoughts?
I've been having exactly those thoughts too, including them locking together. I guess great minds think alike.
I imagine they would swing a few plates apart and shoot a pseudopod out of the gap, then spread them out farther to make room for swallowing a victim. It's probable they can soften, resculpt & recolour their exterior plates to match new surroundings, but I'm thinking it would take a few hours or a day to do.
Hmm... that would imply it has concealed openings on it like a secret door, my evil DM mind is now imagining a Rogue exitedly crying "hey, I think I've got this secret door opeaarrrrhhggghhhhh!!!!!!!!!!".

How much would one weigh? A gelatinous cube weighs about 15 pounds per cubic foot (15' cube, 50,000 lbs = 14.81 lbs/cu'), so a 500 cubic foot Carnivorous Wall (10' by 10' by 5') would weigh ~7500 lbs assuming the same density. It's a Large ooze like the Ochre Jelly, which weighs 5600 lbs, and is about ten times heavier than a Gray Ooze, which has roughly the same area but is ten times thicker (10' dia, 6" thick, 700 lbs).
That looks OK.