Yogart on my rocks?

I am new to Saltwater but been doing freshwater for years.  My Fluval Edge 6 gallon is in cycling stage.  I'm starting to see some purple coraline on the rocks as well as green algae.  I have also noticed the past couple of days that there appears to be what looks like a blob of vanilla yogart on my rock.  It appears to get larger the longer the lights are on.  I took a picture of it and if i can figure out how to post pictures on here....I'll post it.  Anyone know what this might be good/bad? based off description?  Right now, it's about 3" wide by 4" long.  Suppose it could look like melted swiss chesse too...instead of yogart.  Thanks!