Given the tank has pitch black substrate and the only thing on the substrate is the sponge filter it’s hard to miss.That is crazy, good eye for even seeing it in the tank!
If you see the banjo please snap a pic of it. I’d like to see what it looks like after the shed.
Also let’s just hope it’s not shedding like shrimp bc of a growth spurt...maybe you have a monster banjo in your tank now ?
I’m not sure which one did it as I have 9 different banjo catfish in the tank so it’s unlikely I could tell unless I dragged them all out of the tank and even then I might not be able to tell.