Personally I don't think it's relevant to this discussion. Saying that consciousness is more complex than "you either have it or you don't" seems like a trivial observation.
Peter Singer argues [2] that "the fundamental interest that entitles a being to equal consideration is the capacity for suffering and/or enjoyment or happiness" (and that this applies to any being, human or not). I think that this is a much more interesting approach. Yes, this makes things more complex ("where do you draw the line") but it also seems more honest.
1: https://en.wikipedia.org/wiki/Bicameralism_(psychology)
2: https://en.wikipedia.org/wiki/Peter_Singer#Applied_ethics
No other animal can do this as far as we know.
1. Objects can be repurposed for some other use that what they see in nature.
2. Certain objects are better suited than others, though they are similar.
3. A fore said objects can be modified further to increase efficiency.
4. This knowledge is often passed among communities and families through observation or teaching rather than as genetic changes.
>> Both bonobos and chimpanzees have been observed making "sponges" out of leaves and moss that suck up water and using these for grooming
>> Elephants have been observed digging holes to drink water, then ripping bark from a tree, chewing it into the shape of a ball thereby manufacturing a "plug" to fill in the hole, and covering it with sand to avoid evaporation. They would later go back to the spot to drink.
>> Indo-Pacific bottlenose dolphins made up of approximately 41-54 animals, are known to use conical sponges (Echinodictyum mesenterinum) as tools while foraging. ...During sponging, dolphins mainly target fish that lack swim bladders and burrow in the substrate. Therefore, the sponge may be used to protect their rostrums as they forage in a niche where echolocation and vision are less effective hunting techniques. Sponging may be socially learned from mother to offspring.
>> Woodpecker Finches have been observed to use a different type of tool with novel functional features such as barbed twigs from blackberry bushes, a plant that is not native to the islands. The twigs were first modified by removing side twigs and leaves and then used such that the barbs helped drag prey out of tree crevices.