what are silversides?

[fresh]

Hi all,

I keep reading everywhere that people feed their anemones silversides, what are silversides? And can I buy them at the grocery store (superstore for example)

I had fed my previous anemone frozen baby-scallops and it took it fine, and now I bought a new sebae anemone (Heteractis crispa) and would like to feed it something that it will like, and I can buy from the grocery store (safeway, superstore, save-on, etc a bit cheaper that way)

Are scallops ok? or should I switch to something else?

Thanks
Fresh.