What is in this sandpile?

[Coach v]

Anyone know what this thing is? It appeared overnight about a week ago. It continues to increase in size. Only livestock I have not seen is my pistol shrimp, which is not uncommon.

 

[EeyoreIsMySpiritAnimal]

Pics are blurry, or there's too much algae on the glass... I can't tell what you're asking about.

 

[Rick's Reviews]

Your sand looks fine

 

[((FORDTECH))]

Is it white mold ? Did something die there and it’s rotting. Hard to tel with pic