A weed. Did you sterilise the soil?

Where is the seed mix from? Could be fake succulents.

It came from cactusstore.com and grew from one of the seeds.

I'm eager to see what it does as it grows. Are you going to pot that one up?

Yes laticauda, I’m going to keep it. It’s a cool plant, and also the stem appears to be hardening, which makes me think it’s a succulent after all.

It does look like a caudiciform seedling but I've never known any caudiciforms to grow so fast!

I just googled that and I didn’t see anything that looked just like it. Now, I am giving it 24/7 light but I don’t think that would account for such a quick growth rate. This may actually be the quickest growing plant I’ve ever grown, succulent or not.

In the seed assortment there were a couple of seeds that looked different than the rest. Most were black and disc-shaped, but there were a couple that were long and slender and covered in white fuzz. Right after it sprouted it looked like one of those.

If it grows so fast, I wouldn't think it is a succulent. But what do I know - I never grew any from seeds :)

It may not be a succulent. Still it’s looking like a cool plant.

The only things that get to that size in 8 days are WEEDS. OK it´s a COOL weed but still a weed.

Or certain vegetables. Maybe it'll be something edible.

I wonder about your 'weed' seedling? Did it grow big enough to be ID-ed yet?

I'm so glad you remembered about this, Rina!