yes...
there are critters the "stir" Th's involves then moving small amounts of sand around in the top inch or so.
this is good, if not required, for a healthy
DSB. a
DSB should not be left alone and never touched. it needs periodic minor movement, either from sand sifting critters or from human intervention such as prodding the sand bed every month or two.
as far as the fish. yes, some borrow. this is fine except that they can cause rocks to fall over.
and as far as them eating critters, that could be a good thing or bad thing depending on whats in your tank.
hope that clarifies issues. let me know if you need more clarification
