Unknown soil weed or fungus found in compost bought from a local garden supplier. Small pods are about 6 to 8mm in diameter. Chokes roots of wanted plants and kills them. Tried Weed Weapon to eliminate the unwanted pods. Am thinking of steam treatment next. Never issues green shoots out of the ground. The pods open up issuing what look like seeds. The photo shows a sample in various stages. Not much variation over the last six months.