If the LR was only recently put into the tank chances are it is the remains of dead organisms that perished during the transport/handling/curing processes. Your clean up crew will indeed relish the chance to pick it off and it should go away in a week or so.
does it look like a golf ball with dimples on it?(or at least a half a golf ball?
if it does chances are that its a sponge
i have them on my l\r also (my rock is over 4 years old)so i know there not die off for me
I have some LR with whitish, yellowish, pinkish, and tan slimy areas that look like chewing gum. Actually, only the surface is slimy, the rest is pretty hard. The yellow stuff is crispy, like coraline algae. I believe these are some types sponge. Some patches I've had for 3-4 years. I also have some bulbous tan sponges and a white sponge that looks like 1/2 a golf ball (like wuelfman described). All this stuff is good, and indicates your water quality is good.
The stuff in the pictures ScavDog posted are something else, especially if its that close to dead organisms. That should pass, or you could siphon it up.