If the white lines are a give-away, then the smaller one on the rock is definitely a BTA. Feeding the clown and dottyback tonight, he opened up and there are very obviously 5 small but present white dashes radiating from the mouth - maybe about 1/16" in length. Of course, he's only about the size of a half dollar - sound right?
The other one, more colorful, a little larger and on the sand bed, appears to be splitting so he's not super interested in food tonight... but they came on the same rock from another well-established and cared for tank, so I'm thinking they both are BTA...