luminosi harenae vermis (a specific species of sand worm and ask as many questions as you would like in comments)

It looks a lot like the Yellow Devil

its kind of similar but they are nocturnal and the spots glow in the dark

So it's just a presumably smaller and nocturnal version of the Yellow Devil?

kind of but they are a dark grey and range from dark grey to a pale sandy grey in color. they are also smaller and faster and more aggressive

how big?

like maybe about 15-20 feet in length

the juveniles begin at 5 feet

yellow devils are 30 stories when fully grown

wow so yeah the ones that I made are a lot smaller