Help Identifying Part?

I just got my first Prius and it's a fixer upper for sure. A lot of the parts need to be replaced and I'm defintely doing my best to replace what I recognize but there are some parts that are completely alien to me. I've tried looking through all the schematics diagrams in the manual but I still can't quite pinpoint what some of the parts are. I was hoping one of you would kindly tell me what part this is?

 

Hello,

The part is in the back right in the trunk, next to the battery, if that helps.

 

Thank you so much, I greatly appreciate the quick feedback. That's real neat that it does that, I'm glad I didn't just ignore it. Going to get ready to order one now and hopefully be on my way to a functional Prius soon. Thanks again.

 

I have actually, I did a lot of calculating of costs vs. benefits before buying the car and was made aware before buying that repairs could be expensive. I don't have any error code readings yet and very little of the car's history is known to me but it is obvious that there was some damage done in the trunk, I'm not sure if it was a wreck or if they just had something in the back ram around into stuff but it seems very minor so far... We'll see though, fingers crossed!

 

Thank you for the source, I had actually seen the diagram that is in that pdf before but I didn't recognize it earlier and it didn't have any of the text body with it. Looking at what I photographed and what is charted in there, I can clearly see it now but it was difficult at the time to differentiate the parts in all the charts. All the extra information in there will surely be a great resource for me. Thanks!