Pleiospilos' blooms generally only open fully in the afternoon, with some warmth and direct sun. And if the soil is too dry, blooming may also be aborted. The window of opportunity is only a few days, after that if the conditions have not been met, the flower dries up and you have to wait again until next year. Since you have had it for one month, I can't tell if the bloom was about to open at the time you got it, or if it merely had a flower bud still forming. Regular watering is also crucial to sustain flower bud development. If watering is inadequate, the plant will use its available resources to stay alive and bypass flowering. "20 drops of water" is not really the right way to take care of these plants. If you use an appropriate soil mix in a pot, you can drench the soil during active growth and blooming. More reading here x

I hope you find out which plants you have. Frithia and Fenestraria require completely different watering. Fenestraria leaves are completely smooth, Frithia leaves are covered in tiny bubbles. Three inches tall sounds like Fenestraria, that would be pretty huge for a Frithia. I think you can potentially grow Fenestraria and Pleiospilos together although I don't. Both have very low water needs, will become dormant in very hot weather, and grow best in spring and autumn. The difference would be that Pleiospilos thrives on full sun and heat while Fenestraria doesn't like heat and prefers a little shade in summer. Both have large showy flowers, Pleiospilos usually orange on short stems, Fenestraria white or yellow, very occasionally orange, and on long stalks. Ignore the tag. Bright light is poor advice, both plants will do poorly without direct sun although they might survive for a while. Fenestraria may flower in both spring and autumn if you grow it really well, but Pleiospilos will probably only flower in one or the other. Only water when the soil is completely dry. Don't water thoroughly unless you have extremely fast draining soil, probably in a clay pot. Generally water lightly and fairly often, don't subject the plants to long droughts. Water especially lightly if the plants are dormant in summer. Once or twice a year when they are growing strongly, you can give them a soaking. If your Pleiospilos ever develops more than two pairs of leaves you are overwatering, cut back and aim for just a single pair of leaves by the middle of summer. If your Fenestraria's oldest leaves go mushy and die off, or any leaves develop splits, then you are overwatering.

H, Argyroderma is the Latin/scientific name for the genus. "Split Rock" is the common name, but it can also refer to other plants. The brown, shriveled parts are probably just the remains of dried up leaves from the previous growing season, so I wouldn't worry about them. How do you water them? Argyrodermas generally like regular light waterings. -R

drmedusae, if you live in a zone 6 climate that isn't desert or mostly arid, this plant will only need a few thorough drinks of water per year at the most, especially if you keep it indoors. They are highly succulent and can go very prolonged lengths of time without water. Additionally, if you wish to lightly water this mesemb with mist, you really need to put it near a fan or some other ventilation source to prevent moisture from being trapped in the small crevices between leaf pairs. IME, the best method for watering these is a 'light' bottom watering, most often done during late summer/early fall or in early-mid spring, depending on your climate. In a zone 6 climate, my best advice would be that if you got another one of these plants, plan to NOT water it at all during the summer. Place it in a very sunny spot for the whole summer. Just make sure the soil temperature doesn't get too high, or you might get root death. If the inner leaves become soft during the summer as well, you may want to give it a small bit of water; I don't know what kind of zone 6 you live in or if you keep the plant indoors or out, so the leaves might not soften up. Misting the plant during the summer may also be a good idea, but as I said earlier, this requires good ventilation to stave off rot. I'm sorry your Nelly is going by the wayside :-( but gardening is a learning experience, and everyone on here has killed their fair share of cherished plants. Live and learn :-)