This is similar to perceiving how an entity presents itself. This could be such things as having horns, or pointed ears, or wings, etc. Spirit entities of any kingdom, phyllum, order, or class may occasionally produce flares. Flares appear as demonstrated in the illustration here. Any entity requires energy intake of the same basic types of which it is comprised, in order to maintain itself.
Some entities can go for longer periods of time without additional energy than others can.
Some entities may also be able to reproduce themselves in various ways in order to create new entities. Entities of any kingdom, phyllum, class, etc. may engage in all of these behaviors at one time or another. I will begin with constructs. They could be likened to very sophisticated computers and robots, but that would not be an entirely accurate description either. They are more like genetically engineered creatures.