What is this bug? Looks like a tiny grub.

[nicolehuntah]

I’ve captured this little critter and I’m wondering if anyone knows? I tried some reverse image searches and clicked through threads but I’m not totally sure. It does roll into a ball.

I don’t have many fish in there so my arthropod population is crazy at the moment. It’s been 6 months with a lot of opportunity for them to multiply

 

[keagan]

Its really hard to see what your looking at in those pictures a light background helps. Your description of it rolling into a ball coupled with it's general shape makes me think intertidal isopod eg the family Sphaeromatidae.

Edit: does it roll into a tight ball like a terrestrial isopod? Or a C shape?