Recreating a Feature From Nullscape for My Biome 1.19.2

https://github.com/Stardust-Labs-MC/Nullscape/tree/1.19.3
Nullscape has these rooty like glowstone things that I want to simply clone and replace with coral blocks and put them in my biome which has a surface of concrete powder the issue is I can't seem to understand how the generation of these roots happen the most I've been able to do is ones in the second and third image I simply want the rooty thing nothing else to be like plants from the floor