Are the pieces actually rooted? They look like new cuttings.

And they're currently low light (though that may be time of day) and in a soggy peat soil.

Post in the Cacti and Succulents forum. You will get an identification and very specific care advice there.

I think this plant would do better in terracotta than plastic, the soil does look wet, these need to dry out in between watering. ( not desert dry mind you). And bright light.