I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
That is most likely a fungus called slime mold. It is not really attacking the turf but rather growing on it's surface. You can usually blast it off with a hose spray nozzle. The following web sites offer more into on slime mold:
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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