My 40 year old cactus, home grown from seed - what is it?

[Aridane]

As a child, I grew this cactus from seed.

It is now 40 years old, having survived decades of lack of care, and is 2' tall (including pot).

Any idea what it is?

(sorry for duplication)

Looks like a pipe organ cactus maybe? Well done!

en.wikipedia.org/wiki/Stenocereus_thurberi

It looks a lot like one I had many years ago, I'm very impressed you have kept yours alive so long. Mine was a pachycereus pringeli.

No idea on species but just wanted to say, it's brilliant!

Aw, thanks

Looks like it could be either!

Nope, sorry, it's definitely not S. thurberi, and quite tricky to identify due to being rather etiolated from low light levels. I'd hazard a guess that it's a Ferocactus, and possibly F. hamatacanthus, which would normally be a more globular shape.

...and I'm going by the fact that is hooked reddish central spines and the rib shape.

Oh my goodness - looking at pictures of ferocactus (hamatacanthus), which are barrel shaped, my poor chap must be very etiolated

And he is curved, must be from leaning to the light

If I put him outside for the summer, will he fatten / barrel up?

Or is it once etiolated, forever etiolated?

Unfortunately, you can't reverse the etiolation, although if it's given much better light the new top growth should normalise. If you want to put it outside, you need to wait until all risk of frost has gone, so about May. But don't go straight from the dim indoors to bright sunlight as it will scorch! Do it gradually.
And congratulations on growing it from seed all those years ago! That's quite an achievement!

As a child I given a pack of cactus seeds and planted them in a tray of garden soil.

With a beginner's and child's luck, loads germinated. I transplant a pot the one you see above - but mother, not realising there were loads of tiny seedlings in the tray thought it was just a tray of dirt / soil and chucked it

She still feels bad about it when I periodically remind her about it.

I thought I might try to reprise my childhood -greenfingers- luck and try growling seed.

I bought this kit on Amazon - www.amazon.co.uk/dp/B07KFJZMDN/ref=sspa_dk_detail_0?psc=1&pf_rd_p=454d2892-a6d1-488a-b5c1-57058b38bc92&pd_rd_wg=6qTN6&pf_rd_r=S413ZCX82BC8H5VWNQM4&pd_rd_i=B07KFJZMDN&pd_rd_w=dTMp0&tag=mumsnetforum-21&pd_rd_r=ebb09bf4-3152-11e9-8be3-4b5a83f21e01 - which looks fun. But am trying to hold off planting until spring

Have fun with that Aridane! And they guarantee your money back if they fail to grow! That's optimism for you!
The Feros should be easy enough, but the Pachycereus pringlei is one of the slowest columnar cacti to grow, so don't expect too much from it.

In which case I will start with the Ferocactus Robustus and take it from there!

Thanks for all your help on this and other cactus / succulent related threads.