Not sure what to make of this. View is from the basement and above it is the exterior porch concrete pad. It does not appear to be structural based on the construction. Is this part of the form that was not removed after the floor was poured.
Typically around here several builders have converted the space under the porch into a storm shelter. However the glass block is not acceptable for a storm shelter. The supports may or may not be structural, it depends on the reinforcing steel used in the slab. Was it designed by an engineer or was a stamped set of plans used?
Typically not structural, it is just the form for the slab. With that being said, if it is an older home there may not be rebar in the slab giving it the structural support it needs. Most of the time though the slab is sitting on the foundation (at least 2" or so) against the house and IS self supporting. Did you see an issue?
No, I did not see any issues. The home was built in '87. The slab was level and cracks. Just haven’t see this before.
I’d bet that’s temporary shoring to support the forms. It’s too haphazard to be permanent.
Back then they use to always leave it in. It’s saved time and it also Allowed for quicker and cheaper means of running electricity And made it easier if someone wanted to finish off the ceiling.
We call it a cellar in our neck of the woods. It is used to hang sausage in the cold room and make wine. All the Italians leave the forms on the ceiling for this purpose. They do not use rebar all the time but I have never seen one fall in my 40 years in the SSM On. Things to look for are sagging of the plywood sheet in the middle third of the form. 
Support is sometimes needed if the sheet is coming away at the ceiling.
Thanks guys. This has been real helpful.
The plywood and 2x frame is adding very little support at this time. Except around the perim., shoring would have been in place to hold the porch slab until design strength was achieved.
Leaving that used formwork in place is a perfect way to provide a lot of hiding places for termites and other pests. There is no real legitimate reason to leave it there other than pure laziness.
what about termite damage? has that ever been an issue for you guys, considering concrete is very porous and moisture would stay in between.