Second Step's Second

The next place Lumi wandered was this marvelous expanse of ice. As the dusk turned to night, the pillars stood in dark contrast to the brilliantly glowing spots beneath the ice's surface. Careful hooves led Luminosa to a small patch of glowing ice. She dipped her head low, honeysuckle eyes reflecting the blues of the plankton below. Such wonderful creatures! She assumed they were some type of bug, but she would have been mistaken. In front of her, an icy spire contorted and twisted under its own weight, its fracturing body looking quite unstable. In the distance, another bowed back the the ice from which it had risen while many others still stood proud. What could cause the ice to do this?