From Zelda Legends Wiki
There are many Ghosts in the Zelda series. Most of them are known as Poes, but there are some other ghosts in the series, some are hidden, some are important to the storyline.
The Blue Bubbles and Red Bubbles are also a ghost-kind creatures. They attack by coming to Link and making him invulnerable to do something. The "Ghost Smoke" in Earth Temple is possibly the smoke around the Blue Bubble.