Anyone seen this before?

I went to my high school today to help with some graduation stuff. The teacher I helped is in what is known as the “E-Building,” which for the most part has these smokes (sorry for the quality; i took this on an old phone years ago):

Now, I know what these are. However…
Today, I went down a hallway I had only really gone down a few times during my time at this school. I noticed these on the ceiling:

Anyone seen these before, and/or have any ideas what they are? Smokes, heats, neither? (Note: the red light was flashing every few seconds, not steadily on as the picture suggests).

Here is a close-up, if that helps:

Those are old Simplex 4262-5 ionization detectors from the early 70’s, originally made by Statitrol. I believe wiley209 has one.

Yep, I certainly do! The K-8 school I went to for kindergarten has one in their cafetorium, while other areas have 4255-1 mechanical heat sensors and newer Simplex duct detectors (with presumably the same 2098-9201 detector heads as that first picture.) The school was built in 1974 and had a Simplex 4208 system (they still do, but now there’s a 4005 or something tied into it for the duct detectors.)

Well, that does make sense - that part of the building has 4040s, which are from the 70s. They looked so new, I assumed they were newer. Thanks!