what i'm using is like real tiny stones. i use this in the aquarium i have my turtle in. she walked up to the box, put one paw in, then another, kind of felt around and she turned around and left. we have 3 other litter boxes as we have multiple cats and i'm afraid if she doesn't like the feel of this, she will use another box and i'll have nothing. she's been using this spcific litter box since she's been recuperating, and i'm afraid this will scare her away. shall i leave it in there for awhile and maybe she will go in later? she must have had to pee or she wouldn't have gone in i wouldn't think.