Please help me identify these old models!

My parents moved out of my childhood home and sent me a box of models I had collected around 12 or so years ago. I was able to figure out what most of them were pretty easily but I could use your help identifying a few. I'm not sure if they're just older versions of current models or if they're models that aren't made anymore.

I think these are Necron Canoptek Spyders but the ones in the official store have these big cannons on their backs so I'm not quite sure if these are the same thing.

This looks most similar to a Tyranid Zoanthrope or perhaps a Neurothrope but it lacks any of the appendages, is only a single model instead of a set like in the store and is metal instead of plastic.

Any help would be greatly appreciated!