What is the point of "create hairball"?

I was messing around in the console the other day, and I saw a command, something like ‘create hairball’ or ‘create_hairball’. I typed it in and executed it, and it made this little black tentacley thing. It looked pretty cool, but what is the point?

It was some sort of test valve left in.

Its a clue.

Its something valve left in from when they was testing ropes i think

Remember in the very beginning of Half-Life 2 when you’re looking at the citadel after the teleporter malfunction, and Barney hands you your crowbar?
Well, the little black things you see falling out of the citadel that you can’t identify are these hairballs, they are meant to look like scanners to the player.

To add to the mystery, it is in every source engine game but only works in games using the EP1 engine or above. (It will crash a game not using one of those engines)

Some say they where an early test for liquid physics
I.E the portal 2 propulsion gels and whatnot.

Basically them trying to emulate the effects of many props whilst avoiding the mass physics that would otherwise be involved, by spamming sprites.
I’m not convinced though.

No, those are little scanner sprites, not hairballs.

They are wrong. The hairball entity is actually a mass of rope entities (about 100, made form 3 segments each). The hairball then moves around and physically simulates the ropes.

It was just a test to see if ropes worked right.