What type of photocell is that?

Going by the ridges it might be a DTL? I've only seen Fisher Pierce PCs dryrot in that fashion though (all uneven, giving the PC a camouflage look lol) but FPs didn't use the ridges except the older pre-1972 ones, but they used the hard plastic that turned yellowish instead of powdery.

That's what I was thinking, but just has an odd wear to it. Still looks cool.