The crystalline entity was much larger than a Galaxy-class Federation starship. Despite its size, however, it was not more powerful than such a starship; the crew of the Enterprise were confident that they could kill it with phasers and photon torpedoes, and the ship's shields proved capable of resisting the entity's attacks (although they were never tested against a prolonged assault). The shields of the freighter Kallisko, however, proved to be inadequate against a determined attack by the entity.
The entity was capable of interstellar travel at speeds of warp 8 or more. It attacked with rays of an unknown nature that completely destroyed organic matter, somehow extracting the energy for the entity's use. It was capable of stripping a planet of all organic material over the course of several hours. Data speculated that mineral ores containing refractory metals might provide protection, and a few colonists found refuge in a cave lined with such minerals during one of the entity's attacks, but Dr. Kila Marr -- who studied the entity extensively -- suspected that it spared the colonists to avoid harming Data, mistaking him for Lore, who had collaborated with it in its attack on Omicron Theta.
The entity apparently communicated with graviton pulses, although it could apparently understand subspace transmissions as well. The Enterprise attempted to communicate with it, but Dr. Marr interfered with the attempt by using a continuous graviton pulse to create a resonant vibration within the entity that shattered it.