I'm assuming that the other answers were tongue in cheek and that they (other than Len of course) DO know what they are? They're a type of soft scale. The "cake icing" is a protective layer they produce to keep themselves moist and covered while they suck the juice from the plant. You can see the more traditional "scale" sitting like a cap at the top of each piece of foam.
I'm sure some of the insectivores here will be able to identify down to specific name etc, but at least this is a start for Len. Is that a help?
