In most cases it will be planeria and other detritus eaters that like egg fats and don't stop at the thin casing to get them.
BRAND NEW NEVER OPENED NEVER USED!
"EHEIM Quick Vac Pro Automatic Gravel Cle ...
Everything is brand new, tank only lightly used
for aquascape. I purchased a larger tank for my
Offering a beautiful blue and yellow damsel.
Approx. the size of a gold dollar coin. He's
being a b ...