One thing I really like about Makuta's movie design is the lack of a heartlight. It's a very simple detail, easy to miss, easy to not make a big deal out of it. But also that could be a very significant choice on the part of the designers. It works for Teridax of course, he's literally heartless, but I often think about if the same would be true for the other Makuta as well. They do have life-force, but they're not the same kind of creature as anything else in the MU, just sentient energy-gas contained in mechanical armour. They don't have biological processes for a heartlight to indicate. Maybe they once did, when they were biomechs like everything else, but after their evolution those little system-function lights were removed for being extraneous. But then, we know from Teridax assuming Dume's form that Makuta can shapeshift to have heartlights, so it could be down to personal choice which still present one and which don't bother with it or actively choose not to have one in a display of strength.
And of course all of this is further complicated by the dubious canonicity of heartlights to begin with. The movies have them, some of the books mention them, but the sets never did, so we're left guessing about them a lot of the time. But I don't know, assuming we can count them as canon and something that would be present in most MU species (Nidhiki, Krekka, and Sidorak all have them in the movies, and I can't really tell for Roodaka. There might be something there in the cavity that gets filled with the Makuta Stone? Oh and the Turaga Metru don't have them, for some reason[??] Lhikan and Dume do though) Makuta not typically having them feels like that much more keen attention to detail.
