In humans, soft poop is really one long, mostly continuous sausage before it comes out. It gets its "link" look because we tend to pinch off lengths of it with the anal sphincter as the poop emerges. If a person pinches hard enough, the poop separates into several turd units. If the person doesn't pinch that hard, the turds may stay connected.

If you can remain sufficiently relaxed, you can produce an awesomely long poop that will coil up inside the toilet.

Snack
Viewing Thread
How does poop stay together, like in links?