Thanks for the quick responses! :) I haven't been able to spot any critters on the leaves(? fronds? branches? not so sure about terminology here!) so far. The cactus pictured is an Epiphyllum - I just did some research and identified it. Whatever is going on with it is also affecting my Euphorbia milii - there are little brown spots and holes appearing on some of the lower leaves. I water them sparingly with room temperature water and allow it to run through. They're located close to a window in my kitchen... I don't think it's too drafty there but I could be wrong. There are more pics of the problem in the link. Thank you for responding!

To make sure it is scale, try to wipe them off with a cotton ball/q-tip moistened with rubbing alcohol (or even a tissue). Scale would come off easily, with just little pressure. If squished, there would be red 'goo' - blood. Otherwise it is not scale. In last photo, the tips are white (not brown). Could be just drying of the leave or it may be mealies. Is there any fluff? cottony-looking very fine webbing? See if it could be wiped off. Are they all potted in communal pot? Some have different watering needs. Btw, 6feet away from window is typically not enough light for most succulents. Rina

They need lots of sunlight. Maybe still not enough indoors. Any obstructions (trees or other vegetation, curtains...) will make light 'indirect'. I think that spots may have started as mechanical injury; but check 2 bigger ones if the leaves or spots themselves are soft. If there is a scab over, it should be OK. Otherwise, maybe even remove those leaves. Make sure the potting mix is thoroughly dry before every watering; use bamboo/wood chopstick or skewer or even pencil to test deep inside the pot. Bottom plant doesn't look that great - hopefully only because the protective powdery coating (often referred to as 'farina') seems to be rubbed off. Try handling the leaves as little as possible. Check the leaves if they are soft/limp - they should be quite turgid. IMO, it needs more light. If you have access to any outdoor space, they would benefit being there - but do not put them into sunlight suddenly or they will burn. Outside light is more intense and plants should be acclimatized. Can't tell for sure how low is the soil level in that pot, I like plants sitting higher so no leaves are really inside of the pot, if possible.

I don't believe it is oedema. I don't think it is sunburn either - but possibly. At least on first plant. Ppl posted photos of similar damage, and it is likely caused by something chewing on it while still younger. Those 'bites' have scabbed over. As the plant grows, rosette opens up more and damage is more visible. You can see it is sort-of regular. Very young growth is usually most juicy/succulent, and it is often first to be chewed on. One doesn't have to see the bug or pest for it to happen...and just because other succulents were not damaged, it doesn't mean it didn't happen to this one. I actually witnessed this to happen. As Dominyka said, those leaves will eventually grow out, and plant will look better. April If you don't mind here is a suggestion: hope those metal tins have drainage hole(s). If not, they should be drilled or poked in. And if possible, top up the potting mix so the plants are not so deep inside of them. Metal heats up more than terracotta (didn't compare it to plastic); and plants are even 'hotter' if they are deeper inside. And it restricts air circulation too.