Hilarity & Amazement, All In One

Ever since I first set foot on barnacles, I've hated the darned things:  they puncture & slash your feet like you were their most egregious enemy.  But recently, I found Siamese twin ones attached to a sand dollar 

(which in itself is new this year:  in all my decades of life, I've NEVER seen barnacles choose sand dollars as a squatting spot; not sure what that signifies), with an obvious divorce having taken place, so I wanted to understand barnacle anatomy better.  

I've always viewed barnacles as perhaps 1mm up the totem pole from rocks.  But then I found this schematic, which totally blew me away...and at the same time, caused a massive abs workout from guffawing.  Notice how complex this creature in fact is!  He's even got certain {ahem} appendages and cavities!

Here's a magnificent view of a live one:

And for a bit more mirth, watch this unbelievable snippet.