The key!!! Or at least, you assume this is the key. There's an Aminara Tower glyph near it, which is strange. There's also a flask of what appears to be medicine, some pills you don't recognize, and... another worm-like corpse?

Seeing it next to the glyph makes you wonder if the corpse could be a...

No, that's ridiculous. Why would there be residents in your house?