Sand sifting stars will die in your tank...they run out of food and will eventually starve. They are better left in the ocean.Ceriths are not sand sifters, nessarius snails do this.
White sand stars are good for sifting also.
The sand-feeding sea cucumbers are some of the best sandbed cleaners and agitators the aquarist can keep IMO, and many are inexpensive and readily available. Many of the species from the genus Holothuria, for example, are prolific detritus consumers able to literally ingest the top layer (1/2” or so) of the sandbed, clean the fine grains, (digesting detritus particles, bacteria and microalgae), and then expel it. This vacuum cleaner-like behavior keeps the sandbed looking great, while requiring very little maintenance on the aquarist’s behalf.My cucumber doesn't really dig--just mops up the surface of the sand.