Calling all Eames Experts! Can you please shed some light on this shell chair?  

Odd indeed vintageobsessive.
Possibly a shell that was altered by someone who didn't like the shock mounts?
Can you tell what the inside of the "shelves"might be made of?
Since the screws don't go through to the seat, it has to be a thick bar of something. Maybe rubber? I doubt it is solid fiberglass, as the screws would strip out.
The shell looks remarkably close to an Eames shell (at least from the front view). Hard to imagine Charles settling for such an "un-delicate" solution to the underside... A side view of the shell would be interesting to see. The base legs are completely different from any Eames X base I have ever seen (with one possible exception I have noted below)
IF… it is not a home made alteration/repair, it could possibly be a transitional / experimental base made in the 1953-4 time frame. The speckled paint/coating on the reverse side does resemble the coating used on some of the upholstered shells from that time.
I seem to recall a couple of vinyl or leatherette upholstered shells with odd legs (wider stance legs-- possibly like these legs) being sold as Eames shells, and they were in the 1954-ish time frame, but I don't recall seeing the shelf on those. Perhaps there was just no photo of the underside and that's why I can't remember them. Either that, or the undersides of those were the standard shock mounts, and it was just the legs that were different. I believe they were first on ebay, and then later on a dealer's site on 1st Dibs. A little over a year ago.

Thanks, Eameshead. I was really hoping that you would chime in.
I've seen a lot of shells in my time but never anything like this. Absolutely no identifying marks. Most period reproductions or knock offs are usually easy to spot because the proportions of the shell are "off" - not quite right. Everything about the shape and proportions of this shell points to an Eames original and yet the bottom is something that I have never seen before.
The speckled backside is heavily textured not smooth.
The "shelves" are hollow and look indeed to be made of the same fiberglass that make up the shell itself. The X base was attached via screws directly to the base (no washers) using what looks to be a U clamp.
I've added more photos.
This has got to be a hack right? It's just too strange and I'm at a loss.

Thanks for the additional photos vintageobsessive.
Now that you mention the heavy texture on the back, I do vaguely recall that those other chairs I saw online may have had the heavy texture on the back too. But I am pretty sure I would have remembered something as unique as the "shelves" if I saw them. Thats all I have though, aside from my above post.
So it seems like there are three possibilities:
1) Home repair / hack job
2) Knock-off production of some kind (especially if there are others)
3) Super-rare production, experiment or perhaps prototype. (but my guess is Eames wouldn't have put out something with a rough back like that, or the "shelves" for that matter)
My guess is number 2, because I have seen that rough back thing before.
(But I guess it could be a combo of number 2 AND number 1, as someone could have bought one of the knockoffs with the rough textured back, and THEN added the shelves?)
Hopefully someone else has seen these and has a simple answer!

Thanks for the comments. I appreciate it.
I'll do a bit more research online to see if anything comes up.
Cheers.

Ha! Was in line on this on Kijiji! $45 on this "eames style" seemed too good to be true!

I think it is a home made repair. Then sprayed with the same product used in truck beds called rhino liner.

Joshua championship - lol took a chance. Not much to lose and all indications pointed to Eames (no photos of underside and at that price I didn't even bother to ask). Easy enough to make that money back (if not a bit more), 🙂
Amazake: if it is a hack (which I thought could be the case initially as well) it is extremely well done. The edges where the top of the shell meet the bottom are clean and someone would have to have mad masking skillz to have the edges so cleanly finished all the way around.
Cheers.

I can't tell from your photos exactly what the texture looks like, but here are some pics of Rhino Liner for comparison. (I could mask off the chair pretty quickly and completely and I don't paint for a living or anything, I'm just good at detail work.)
A Rhino Liner sprayed hack seems more likely than a super rare prototype that even Eameshead has never heard of, simply because Rhino Liner is a product commonly used to cover flaws (I think, anyway...automotive stuff is not my forte, I'm just guessing from the before & after photos I just saw in my google image search).

The only reason that I hesitate to go with the "hack job and rhino liner" theory is that I feel like I have seen these rough-backed shells more than just once or twice.
I lean more towards a small run of early knock-offs, all with the rough back. Probably done in the same time period as the originals, rather than recently. My thinking is that someone couldn't figure out a way to make both sides smooth, so settled for one.
A very small run of strange knock-offs might STILL qualify as a period correct "hack job" though!
(Of course mine is just a seat of the pants guess, like everybody else's. Fun to speculate though, and you never know when that one verifiable sighting, or old photo, or bit of additional info will connect all the dots..)

I get your point, I just thought that since Rhino Liner is such a common product it might stand to reason that more than one owner of a dinged-up shell chair thought it was a good idea.
ETA: IF it even is Rhino Liner or something similar---like I said, I can't tell from the OP's photos.

Yeah, thats a good point too spanky.
These shells have been collected for so long that there is plenty of time for any good repair solution to be repeated. Even the recent ones.

I don't think that this is the same stuff as the Rhino liner as while it has the surface texture it also has a paper-like handfeel, not rubbery like the rhino coating would be.
Regardless, no harm no foul. It was worth taking a chance given the asking price.
Thanks all!

vintageobsessive – I believe there was a company in the Midwest (maybe in Iowa or Nebraska?) that made fiberglass shell chairs that looked awfully close to the Eames shell.... until you saw the back side.
I saw one in person years ago. It very clearly had been laid up by hand and looked quite a bit like yours. My research indicated that it was not Eames but instead a handmade, low-production, period replica, and I think the same can be said for your chair.
That said, I do find it more interesting that your run-of-the-mill shell chair.
Oh, and have you compared its dimensions with an original? I think you made find a difference, particularly around the arms.

Thanks teakhound, this is interesting information. I have never heard of a midwest company making period reproductions.
Great idea about comparing the new chair to an original! I took your advice and did a side by side comparo. The chair on the left is my 2nd gen Eames shell on H base and the chair on the right is the mystery chair.
It's funny how, on its own, the mystery chair looks very much like an Eames but a side by side comparison clearly indicates nuances in the shaping which wouldn't be readily perceivable until the 2 chairs are placed together.
Cheers.