The icy spikes are called penitentes, and they form at high altitudes here on Earth when irregularities in snowy surfaces are exaggerated by solar energy. The sun's energy gets trapped in icy furrows, causing ice to sublimate, which means changing from a solid directly into a gas. This action essentially carves out ice spikes.
Penitentes only form between 30 degrees of latitude from the equator on Earth. The icy formations can only form when the sun is overhead as much as possible. The moon Europa is believed to have similar conditions between 15 and 20 degrees latitude from its equator, giving the icy moon a spiky belt that could be disastrous to any probes trying to land there.
Europa is believed to harbor an ocean of liquid water beneath its icy surface. It is a target for future probe missions because scientists hypothesize that conditions beneath the ice could be conducive to life.