Hi, i noticed something interesting growing in a small section on the side of my foundation, in my patio. It is a four year old house in Houston, Texas. Please see attached Picture. This nasty stuff is yellow, and quite hard. It showed up about 4 months back in the same location, and the only way i got rid of it was pouring Bleach over it ( you can see the black in the center ) Now it has come back.. the only thing i can suspect is moisture retaining after I water my plants that are in the patio. Any suggestions, on what this is, and is it dangerous. What are the remedies to get rid of it/ prevent it.