I like the textures you used, but the overall shape hugs the borders a little close and isolates your tile. I would've like to seen those cracks incorporated; maybe if the texture were set to overlay it would blend in the gray more and look like some kind of gash; I dunno. just making a suggestion. I like the look, just not the execution. second look, if you just continued the one middle crack line that would've worked, too. because now I see a piranha head with the moon for an eye. but the cracks are giving the border away.
anyway, keep tiling; happy happy