gnawed/corroded stem on seedlings, fungal?

[Scooty]

What is this? The plants look otherwise healthy beyond a bit of curling and thinness. I planted more than I need, and these are mostly seedlings I don't plan to use, but I'm still curious nonetheless. There's almost a corroded look to the stems.

[Scooty]

Well after looking through a lot of pictures and going through a few sprays. I just wanted to report back this is damage by way of fungal gnats, in case someone runs across a similar issue.