Looking for advice on caring for a mantis shrimp

[asylumdown]

As the title says - how often do I need to feed it? Is standard frozen food OK (Mysis, brine, pacifica plankton, etc.) Do I need to target feed with tweezers or can I broadcast feed? Anyway to tell how large it will grow?

No idea what species, it was a hitchhiker in someone else's tank that now lives in a dedicated pico tank just for it. It's about an inch long.

I tried target feeding it last night after it dug a burrow for itself, it came out and grabbed the mysis, but after a few minutes of munching on the top of it, it just let it go. I'm not sure if that means it wasn't hungry, or if it doesn't like mysis? It seems very curious.