tuumi, i forgot to mention that the white on the tips of your bubbles is totally normal. earlier, you mentioned that they were bleaching when you had them in direct lighting. its natural for some to have white tips. hope everything is going well...popped EV's ITW onto the turntable recently...many thanks.
the jury is still out on proper classification of these. its possible there are two different species, some that exhibit the white tips and some that dont. there is also a distinct variation in the tentacles. some are much more forked and divided, while some are more simple and bubble like. common names very as well, the forked ones may be referred to as "warty mushrooms," while the more bulbous ones are frequently called "blue bubbles." both tend to occur in similar color morphs, from red to green/blue, and each can be found in the same habitat.