My friend didn't know the name of the plant but she'd had it for about ten years, and she knew her mother had it in her house for at least twenty years before that. (She inherited it when her mother passed away.) It wasn't near a window so doesn't require much light. She remembered her mother simply chopping off cuttings and rooting them in soil, which is what I've done with the cutting I was given.
Here's a shot of the top of the plant.
Each spike is a three-sided main stem with leaves growing out from it. It's a succulent and has nasty, little, stiff thorns growing out of the "corner" of each side. The big plant was very attractive, upright and yet full. It was such a glossy green that it almost looked artificial.
Anybody know what it is?