Gasket or o-ring?

I have a 2002 nissan sentra se-r spec v with a 2.5l engine that im in the process of rebuilding. Its the QR25DE engine. Can you tell me what the gasket or o-ring is called that sits in the bottom of the timing cover? It sits flush in the timing cover between the engine block and timing cover on the side where the oil filter attaches to the bottom of the oil pan. There are two of them. Ive checked with people at the local dealership and have not benn able to get a straight answer.