Interesting "deck" form

[dylansdad]

While doing a remodel of a church (1940's construction) with fire damage we removed the plaster ceiling, which the lath was applied directly to the bottom chords of the joist, and we noticed an interesting type of form used for the concrete floor above.
It appears to be a type of hog wire mesh and paper infill. Just curious if anyone here has seen this type of construction before. It appears to be in very good shape.
Thanks in advance.