Diatoms ?

I don't know if diatoms can kill angels but diatoms are a unicellular algea that have glassy cell walls containing silica. Fossilized diatoms form sediments called diatomaceous earth.
 
Pop-Eye Syndrome can make your fishes eyes seem glossy - untill they pop out, that is. Likely to occur in Irridescent Sharks and Oscars, although I dont see any connection between the two species.
 
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