I'd try something like clam, oyster, etc. and/or snail meat (you can find various frozen/live marine snails to try online, including conch meat, periwinkle snails, babylonian snails, etc.)
The quote below is specifically geared toward
Astropecten spp. (predatory) sand sifting stars, but there is another genus of sand sifting stars called Archaster that is
thought (importantly the diet was
inferred, not studied in the research that this diet was pulled from) to be detritivorous (specifically, they are thought to be microphagous detritivores). I have heard but cannot confirm that
Archaster spp. misidentified as
Astropecten spp. may be more common in the hobby than actual
Astropecten spp. are.
So, with this in mind:
- If your star is detritivorous (which may be a very big if), then you would likely want smaller foods than the suggested below (which is designed for predatory sand sifters). In this case, I'd suggest trying to mix something like TDO Chroma Boost into the sand for your stars to find.
- If your star is predatory (which may to our limited knowledge be possible at this point even if it is an
Archaster sp.), then the below advice (and my advice above) is more likely to be useful.
- If your star is actually primarily a biofilm eater like
Linckia spp. Protoreaster nodosus, etc. (which may also to our limited knowledge be possible for an
Archaster sp.), then it's likely to die regardless of what you do or don't feed it at this point.
I’ve heard they climb the glass when they’re looking for food and can’t find any in the sand bed.
Generally, people recommend large tanks and waiting until your tank is established before trying these (or pretty much any) sea stars, and the star survives on detritus in the tank. Unfortunately, even in a lot of these tanks, after they finish clearing the detritus from the sand, they typically starve.
My current advice to avoid the star staving - which may or may not help, I genuinely don't know at this point (it could take someone months to years of testing it to find out for certain, as sea stars can last months without food):
Target feed the star things like clam on half shell, oyster, mussel, scallop, etc. (bivalves); snail, whelk, conch, etc. (sea snail gastropods); and a good quality omnivore food (like LRS Reef Frenzy or Fertility Frenzy). These are - according to the best sources of information I can find - the sorts of foods sand sifting stars consume in the wild, and the star should swallow these foods whole if they aren't too big - you might need to experiment a bit with the size of the pieces offered to get it sized just right, but generally I'd say err on the smaller side.
If you decide to give it a shot, let me know how it goes, and keep me updated on the long term survival of the star!
