If you build any type of 1x1 tower (or any structure atleast 2 blocks high) you can throw a normal (non enchanted) trident on the upper half of any block that's not the top of the tower and after you brake that block the trident will float in the air without moving (you can still pick it up) updating the block above doesn't seem to do anything either (I even tried powering a piston to see if the block update would make it move but it didn't). You can even place the first block back and brake it again, still it won't drop down. In my opinion I think the trident is getting pinned on the block above too (for some odd reason) and that causes it to practically float. The worst part about this is that for some reason the trident despawns after a while...