Well it definently has mold.

This post was edited by CooperDR on Sun, Jan 18, 15 at 13:01

Well that was helpful!!

Anyway, I would definitely do a re-pot if they were mine :) I don't grow cacti (only succs) but I'm sure the problem is/was that you appear to have no drain holes in the bottom...correct? Also, was there a top part, I guess so but have never seen these 'cactus eggs' here in the UK. If so, did you keep that in place for any length of time as that would cause the mould to grow in a warm, damp enclosed space like that?
I would get them out into a gritty mix else that mould could spread and kill the plants. Keep them moist but not saturated while tiny, let the mix dry a bit before watering but they need good drainage and plenty of light. Did the egg say what type they were? If you need more help just get back to us.

Gill UK

I grow cacti from seeds. Not always successfully but they say to repot when they're the size of a marble.

Yes, I'm sure 'they' do,........but if you have mould growing around them, (or around any seedlings for that matter), which the OP obviously has, surely it's best to get them into a clean non-mouldy growing media......whatever their current size?

Gill UK

Yeah I agree- sometimes mold and rot go together. Also when you transplant them they should be planted a tiny bit deeper. Sand is what I use to stabilize them but sand has it's drawbacks because it can stay too wet. So half of them might not make it but the other half should.

Small grade horticultural grit would be better than sand I think as wet often means cold...and cold + wet = rot, well in the UK anyway!! Aquarium gravel is a possibility, or even chicken grit.
The media in the egg has rather large particles so the seedlings are a bit unstable. It also has large air pockets so the roots may not be in contact with much of it, also a cause of rot. Personally I would make a gritty mix with a small proportion of already gritty cactus mix, but only 25% max, the rest could be made up of 25% each of the small grit, perlite and tiny bark chips, but avoid anything with peat at all costs and yes, they can go a bit deeper :) Just my opinions.

Gill UK