I planted some notocactus seeds sometime in September and many have germinated since then. A few weeks ago, there was an incident where some of my succulents may have experienced frost and I can't be positive which ones (other than the obvious effects: I had to throw many away as a result of succulents drooping and oozing). I haven't noticed any obvious growth in the notocactus seedlings recently and pictures I've taken fail to help me identify growth due to the extremely small seedlings' sizes (see below).
I'm curious as to whether my cactus seedlings have died or not. They seem mushy when probed with a small toothpick, which I know is a sign of succulent death. Is there a definitive way to be able to tell whether my notocactus seedlings have died or they're just going through typical slow growth?