What Sumpin' meant was:
Bubble corals can send out stinging sweeper tentacles that are long & translucent, whereas their feeding tentacles are usually short & stubby. This is how many corals fight for space to grow, by stinging any corals that are growing near them to clear an area around the mother colony. This is also the main reason why some corals need to have several inches around them in your tank to prevent the stinging wars. Galaxy corals are notorious for sending out 5-6" sweepers.
However, some corals have little or no sweepers: the lovely fox coral, xenias, pipe organ corals.
Others depend more on chemical warfare & release chemicals into the water to attack other corals. This is how sponges compete for space in the wild.
Another reason for using activated carbon or ChemiPure in your filter.
Anthony
