bug id

Hello, I built a new tank for my fants after moving, it has been great for about a month, but yesterday I noticed millions of tiny white oval shaped objects covering any exposed soil. I have added Photos below, if anyone has a guess as to what they might be or what to do I would be very...

So I semi-recently set up a 20 gallon long tank and I noticed a small bug on the wood. There are some fungal gnats in the tank so I'm hoping its a larva from them. It's hard to see in the pic but it has a black head and I think I saw it move in an undulating fashion, kinda like a caterpillar...