What's this?

I was finely building an exhibit for axolotls. And now, I haved noticed something weird: it looked like trident. I don't know, how it was geted there. I didn't noticed that, even when i builded that building, it wasn't been there. I didn't summoned that, or throwed trident, but it looks weird. That's all that i kow about this.

 

Screenshot: