Brown cactus with growth pattern issues?

[Geeklet42]

History: A friend of mine planted a handful of cacti as a child, though he's not confident when. I asked how old they were, and his comment was "at least ten years, probably more like twenty." When he moved out, he left a couple of them at his parents. He picked them back up a bit over a year and a half again, and he gave one to me. It was in a window for that time, so I suspect light was fine, but he's not sure if it was watered for quite some time. I have a few concerns about it, and thought I'd post to ask if some of it is normal (I really think not) and if there's anything further I should/could do to help it be happy. <3 (Pics after commentary/questions.)

1. The bottom 2/3 of it are brown/white. I've seen information on corking, but thought I'd ask if it looks like that to people who know better than I do. The skin looks almost cracked, too.
2. It's curved out to almost 90 degrees from where it goes into the ground. Will it be able to hold itself up? The base is super-thin and roots look like they're growing out at an angle to support it. I'm assuming it might be the result of growing in a window?
3. About halfway up, the star-legs that have spines on the end change pattern. When I got it, there were three little guys growing straight up on it. I've since removed them and let them stand on their own in soil. The little guys all have pretty solid lines up - is this normal for that to shift when they get older/bigger?
4. It looks like it's growing roots out of the top part. Is this okay, or something to worry about?
5. The spines on the bottom half seem less existent than on the top. Again, is this okay?
6. The little guys round off at the top. This one looks flat and almost blackened.

[Geeklet42]

I hate to risk pestering with a bump, but I'm looking at repotting and would like to check if there's anything I can do to help it grow.

[Cactus Charlie]

Hey, i'd guess the browning at the base is basal rot probably from overwatering, your compost looks pretty rich, may be worth mixing a free draining compost for them, like 50/50 potting compost and grit is the easiest, but if it is rot you'll need to cut it off to where the cut is all green inside - no brown or dark colours! let it dry and callous for a week or 2 in NOT direct sun, then replant it - and hope it recovers! Chuck away the brown parts and the roots in the soil. Also I suspect this is why its leaning over as its rotted from the inside to out which means so once you find it, its too late to save....The top has definately been cut off at some point, and as for the aerial roots, thats just bizzare, but someone on here'll be able to tell you whats going on there,,, maybe also repot them in single, shallower pots, or fill that pot like 1/3 full of grit before you put your mix in, i'm assuming there are drainage holes in the pot as it has a saucer underneath it? Good drainage is pretty important for cacti to reduce the risk of rot... hope this has helped somewhat, Charlie

[Cactus Charlie]

Could also be spider mites which have damaged it, but I may be wrong on that....

[Geeklet42]

Thanks! I ended up cutting the top off because the base was pretty disturbing in hopes it will grow on its own when planted in a few days. I think I'm going to invest in some sort of pest-killing spray just in case - seems like a good thing to have around. <3

[luddhus]

The bottom 2/3 of it are brown/white.

I think it is corking, but it is very widespread.

It's curved out to almost 90 degrees from where it goes into the ground. Will it be able to hold itself up? The base is super-thin and roots look like they're growing out at an angle to support it. I'm assuming it might be the result of growing in a window?

Probably because it has grown indoors, yes. I don't think it will remain upright without support.

The little guys all have pretty solid lines up - is this normal for that to shift when they get older/bigger?

Not uncommon, probably juvenile vs. adult growth. (BTW, I guess star-legs = ribs?)

It looks like it's growing roots out of the top part. Is this okay, or something to worry about?

Aerial roots. Some columnar cacti grow them, especially on parts that are not exposed to much light. Not harmful.

The spines on the bottom half seem less existent than on the top. Again, is this okay?

Normal, some cacti lose the lower spines as they grow. Or they grow bigger spines so the old spines look smaller.

The little guys round off at the top. This one looks flat and almost blackened.

The top has definitely been cut off, on purpose or by accident.

[Geeklet42]

The bottom bits right around the roots I kind of think are corking, because it knocks almost like wood. But the rest of it was more flaky than woody, and there were actually black and yellow chunks of stem hidden beneath the outer discolored shell. I wound up cutting those out and covering it with cinnamon. The next morning, the skin above that area was softer than it had been and softer than the upper part of the cactus, so I followed another forum's suggestion to cut it. /-: I hope it wasn't unnecessary, but hopefully the bits will be able to grow either way. Hopefully I haven't killed a living thing older than all of my nephews combined. *crosses fingers*

One of the little guys actually picked up a small round black spot of caved in skin - I used a dab of alcohol and a sprinkling of cinnamon on it and pulled him away from the others. Not entirely sure if I should do anything else, or when to pull the coating off or what-have-you, but it's another four days or so yet before I put them all back in a soil mix.