Carl do you mean that you and someone else saw an ET in physical? I would love to see one.
I think that there are some cases when beings residing in spiritual or energetic realms can materialize in physical, but perhaps it is not very common. I do often wonder about this and also the phenomena of physical shape shifting if one allows an ET aspect to come over but what the energy beings have told me is to not consider at this time to even try to do that, but some people say it has happened to them at least briefly. There are lots of fake videos online but one time talking to a lady she showed to me something that happened to her while someone took a picture of her. She had no skills on the use of digital software and her eyes showed up literally with vertical slits and light blue iris, very clearly, and she also said that sometimes people would tell her that she had awesome light blue eyes but her eyes are dark brown. Other people have been able to do that consciously.
What you say about the physical appearance as to how much we can perceive is very very true. This is the reason why a lot of people think that lots of beings look like Earth humans, but sometimes this is really not the case.
Here is current progress on some channeled beings, but still not completed. In some cases I do not get to see their full form, just glimpses, but when they show up in drawing it is interesting to see how they really look like:
This one is of the kind that looks like a devil, but in reality they have an interesting DNA mix, from ancestral goat species (the horns mostly), some dragon DNA (eyes), and the skin of this one is redish-purple, some Lyran DNA, they have very large ears and two pairs of eyebrows.
These ones are reptilian, big mouths and big horns, lots of soft spikes on the head, similar to what iguanas have:
This one is a dark blue Sirian with dark eyes:
This one is Arcturian, of the kind that people describe as being advanced in healing and technology, green wrinkled skin, very big noses, large tongues and elongated heads, not human looking at all and not grey looking either except for the eyes but not really because their eyes are brown with a spiral pattern:
And here is a Lyran man, of the kind that do not have horns but that do have many eyebrows on their long foreheads, large eyes, large ears, noses similar to felines, not looking like how Earth humans look:
Still much work to do to complete them, and then to add the colors.