I was strip mining at Y=11 and I ran into some stone that was taking longer to mine than usual. It was in a little clearing with some lava pools and silverfish came out of the stone. Am I just really lucky and accidentally found the stronghold while mining? Or in the recent update, did they add just random silverfish stone? And if I did find the stronghold, about how far would it be from Y=11? I built a spiral staircase from where I found the silverfish until about maybe 10-15 blocks up and all I found was a cave. And if it means anything, I was playing on Normal.
They're actually pretty useful if you can control the swarm. Just go someplace above the bugs, and just keep punching them. They'll keep spawning, and when they've cleared out enough stone, you can burn them.
Stay fluffy~