Can You Tell Me What This Is Please?

One of the businesses I own is cleaning out rental properties, and I came across several aquarium items that I took home. In these photos are some of the items, and I'm wondering if the filter contraption could be used in my brackish tank for my fiddler crab? It looks like some kind of under-gravel filter which I think would work much better in my tank than the filter I have rigged up.

I don't know how this would work, if I need more parts, etc. Can you help please??



Here's just the filter:

As you said, it does look like some form of undergravel filter with what i presume is carbon in the top chamber?

Personally considering the amount of waste crabs produce i would be more inclined to go with a more significant filter

After doing a lot of googling I've determined it's an underground filter for a round fish bowl. So that helps to know. Now here's a real newbie question .... can I cut the plastic tube between the round bottom part and the charcoal cartridge so it will just be under the surface? Ideally, where should the cartridge be in the water column?

I only have one female fiddler crab and a CAE in the tank so there not much mess going on. The reason I'm looking to see if I can use the undergravel filter is because the setup I have now is so clunky and distracting and takes up a lot of room in the tank.

Charcoal has finished it's job after 3 days and is useless after that. The charcoal you are looking at probably finished it's job many years ago. You don't need it, just cut it away. WD