Quite often various seeds will get mixed into compost and the seeds will germinate and send out those roots, but as long as there is no green growth they should not be a problem. A lack of sun will cause those roots to die in a while.

There's been no green growth, but the roots seemed to be very healthy and showing no signs of dying out. I picked out a lot of them, but they were all very healthy looking, sunlight or no sunlight.

Any nearby trees or shrubs in the vicinity? They will invade and colonize every square millimeter of a compost pile with roots large and small.

The thing about these roots is that they don't seem to be attached to anything. They''re just growing in the pile. If they were coming from some of the oak trees (20-40 feet away), i think they would be thinner and coming out of the ground below the pile.

I'm going to dig around and see if I can make any sense of this, but they don't look like Oak tree roots to me.

They look a lot like the dreaded Bermuda grass. If you have a Bermuda lawn, that's where they are coming from. Horizontal rhizomes, tough as piano wires, with white shoots growing out of the joints going upward to find light. If you don't have a Bermuda lawn already, KILL IT NOW before it spreads.

There's no bermuda grass anywhere near the street I live on, and probably not much in this entire canyon. But I did dig around in the pile and found some of these white shoots coming from what could be roots so I took a couple that seemed to have small roots growing from the other end and I'm going to plant them and see what comes up. I also found that there were roots coming from the ground...I think these white shoots had been chopped up a bit by the time I found them so they may have been attached to ground roots.

It'll be interesting to see if these roots with shoots grow into identifiable plants.

I wonder if there was a plant there before. The dormant roots are now growing.

I’d love to know if you found out what this was as I have it in my compost heaps.

I haven't thought much about the roots/shoots for a while, but I've found roots (not the shoots) in all my raised bed gardens, and since I have some large coastal oak trees close by I'm pretty sure the roots are from the trees. The roots are everywhere, and they were probably attracted by the moisture in the raised beds and especially in the compost piles. The extra moisture in the compost piles must have encouraged and attracted the whitist parts (that look like shoots but are probably just new roots). What kind of trees are close to your compost pile?