I have had these cool looking mushrooms develop in one of my potted plats recently, I think they are really georgeous when I found out they wouldn't harm my plants, my advice is to enjot the intense color while it lasts as each mushromm group only lasts a couple of days at most. I just remove the mushrooms when they die.

It does sound like one of the many 'creatures' we refer to as slime molds. Not a mold or fungi, at all, they are not decomposers (as was once thought) but probably feed off dead organic matter they happen to come across. Slime 'molds' can grow on concrete. Though not a beneficial organism, slime molds are not harmful either, and should be considered something of interest. A picture would be fun! You'll probably discover that it looks different, however, when you go outside to capture it on camera!

I couldn't use that link but I did a search for you and think the link below will work. I could be wrong but the last time I saw that color was on one of my houseplants that had stayed too wet for too long and they eventually grew into mini mushrooms. Could it be too wet? I don't know about you but we have had a ton of rain this year and I've been finding mushrooms in my beds. I have to keep fluffing up the mulch and even moving it away from the crowns of plants to avoid rot. Here is a link that might be useful:

I googled dog vomit fungus - tons of info, one source linked below. Nasty looking, huh? Here is a link that might be useful: dog vomit fungus (slime)