@VanessaS My N. incei is like that. Most of the time, I just see her feet sticking out of her burrow when she is hunting. When I feed her, I get a few seconds of viewing time before she drags the prey into her hole to eat in peace.
I had one that I picked up at an expo. Very tiny looking spider. About one week after I picked it up it webbed up its hide and went to molt. I was surprised when the little one finally emerged and was fully hooked out MM. I did not have a female so I traded him to a guy for credit towards an X. immannis sling and a promise to kick me down a couple of slings if the breeding is successful. Wonderful species and will get another one sometime.