IMO, if these came out within 1-2 days after the night of liver flush, then could be stones. The color indicates, calcified stones. If these don't break after touching with hard stick, then more possibility of being stones. It doesn't harm to use a stainless steel strainer, and after washing these, examine in detail.
If these are not coming within 3 days from the night of liver flush, then these might be parasite sacks.