I have never seen a "monstrose" or crested Aloe
Alfonso

That's aloe cancer, Borrego - it's best if you toss the plant. It might be treatable with an organophosphate insecticide like Cygon (not available in CA any longer) or another one (I've used Orthene to treat one plant) but it's probably best if the plant left your collection for the rubbish heap, so as to not affect your other Aloes.

Do be careful when using those insecticides, of course - they're very nasty.

Thanks for the informed response, Mr. Harris. The plant was given to me just a day or so ago, no problem to toss it. I have three other pieces to go repot right now. Thank you again. Another useful tidbit of aloe information to store away in my brain.........

Really? Cancer for real? Also contagious? Or is contagious cancer some oddity specific to cancer in Aloes? Sure does look like evil spawn from another planet!!

What about the other pieces? Are they from the same plant, & if so, might they have the same thing?

Pirate Girl - I have heard of aloe mites before. Another post on the same subject suggested aloe mites as the cause of this "cancer". I was given a total of 4 large pieces of aloe arborescens yesterday. Two of the pieces have "cancer" and as Jeff Harris suggested, they were humanely tossed. I had never seen it before, but now I know what it looks like. Scary part is that it could spread to other aloes.........