Two holes in boss on casting?

[hope farmer]

In the discussion about the right material for the fuel line there was a picture. In the picture, near the split line, there is a boss with two diagonal holes. What are/were these holes used for and what is the spongy material in them?

[Catfish]

They are for mounting various implements. IH put cork in them at the factory to keep out dirt, bugs, mice, etc... When I first got mine, I thought someone had twisted off all the bolts until I looked a little closer.