Is this your structure?

[Aveege]

I am looking for the owner of this structure. It seems to be a canal for zombie spawner. My questions is, does this structure use any form of fall damage to the mobs or is it just the lava blade below?
Reason i ask this is because i have built a suspension bridge leading towards the area, but this structure was like 4 spots to the right so i wanted it moved.

[Aveege]

So it looks like this is a proof of concept from ak, duel use spawner. Seems to be broken down there. So Ak, give me a shout when you in game

[Akira Doe]

Once I find the mob spawners underground I usually block them off from the tunnel and enclose them (so creepers can't visit) and link them to the Nether. Because of that, I had forgotten where that one actually was, I didn't realise it was so close to your place!

As we spoke about earlier, fixing that "proof of concept" Zombie + Skeleton spawner is on the to do list.

The idea is at the flip of a switch the skeletons and zombies fall down to 1/2 health and are ready to be farmed for XP or the zombies continue to flow and the skeletons are diverted to a grinder (or lava soon) and are farmed for their arrows. The arrows drop down on the player from above while they are waiting for the zombies to build up in the spawner, sort of a double action.