Half-Life 2 Easter Egg - Weird Antlion Egg

Start at the area when you first fight the antlion guard, but noclip though the level to the place where the vortigaunt teaches you how to use the bait.

Then type in the cheat impulse 101, and go to the next area with out the noclip {where it starts loading}.

Once there try using the bait near the thumpers.

I don't know why it's there.