Posted: 28/04/2015 at 19:43
That looks like a Small Redworm to me - it's likely to have come from the manure and they won't harm your plants. They help to break down decomposing organic matter in the soil.
I think the problem for your plants is that the manure is too fresh and is burning the plants. Scrape it off the ground and add it to your compost heap to allow it to rot down thoroughly.