Hi! My name is Horse Clam, and this is my story.

The spat or juvenile clam creates a permanent burrow where it remains for life. Adult clams may live to 25 years.

Just imagine it. You hit puberty and off you go, down into your burrow, for the rest of your life. Kind of like a job I guess. You just plug away in your little cube, day after day after day, the weeks growing to years, your hair falling out and your teeth rotting away, your butt slowly taking on the shape of the office-chair cushion, until one day some bastard comes and makes Clamato out of you. --cue The Clam Signal--

The real question here is how the hell do they get any baby Horse Clams when everyone's firmly ensconced in their burrows for life? Ah, the mystery of the clam!