What is the Statue of Hades?

When Bianca ends up getting killed in the junkyard it was because she wanted to bring back a statue of Hades to Nico. Up until now, readers have only seen Bianca through Percy’s eyes. He believes that she doesn’t care about Nico and was just ditching him at the camp. The fact that she risked her life just to get a statue for her brother shows how much she cared about Nico. It also ends up holding significant meaning for Nico when he finds out that Hades is his divine parent.