Can Anyone Id What This Is?

[Promise]

I have a 75 gallon semi planted tank with 4 female and 1 male convict cichlids well last night i went into the basement to fed the lil guys and found what you see in the pictures
it is only localised to the silicone its not on the glass or anything else, just the silicone
i have googled it cant find anything that it could be?
any ideas what i should do???
the fish dont seem affected by it but to be fair i have only just noticed it!

 

[loraxchick]

bacterial colonies. its normal. will not harm the fish.
cheers