It is a type of slime mold and is completely harmless. It will appear under certain conditions and proliferate in mulch, leaf litter or fallen wood/dead logs. When the conditions become unfavorable (dryness, heat, exposure to sun) it will disappear. Or just rake it away.

its just another of ma nature methods of breaking down and making avaialble.. your mulch

same as her mushrooms... fungi .... etc ... [im blanking on her list of biodegraders]

its natures way ..

you can scrape off all your biodegradable material ... and cover all your soil with plastic if you wish to deter ma nature from such activity ... though i dont recommend such ..

just enjoy it for what its worth.. a free show ...

ken