I was playing 0.4.0 and i find out that Crystallos and Totems can't be killed with a fireball anymore. I think they should be flammable again as on 0.3.5 and even old wiki lists them as burnable.
I would prefer as it is now. The fireflower is very powerful against most of the enemies, the crystallo even walks only in a small area. One little advantage for the little guy is alright, I think.
I do think Totems should stay the same, but sometimes Crystallos should be hittable indirectly with a powerup. In some cases, they can become a nightmare.
Totems are flammable, but they don't have any burning animation. It hasn't been decided so far what should be done with the totem. If it was made to be a boss, it would be silly that it could be burnt down by several shots. Otherwise it would make sense.
The flammability of crystallos was removed because it doesn't make any sense and as said above, the fireflower is very powerful against the most of the enemies.