Saura is not tangible.  You can touch a saura with your hand, and feel nothing from it.  This is believed to be true even of inky saura, as it has never been differentiable before it has properly manifested within a shell.

Saura does not show its nature.  It is simply a bright, golden light at night, nearly invisible in the daylight.  There is no indicator that it is inky, no known indicator that it is possessed or malformed.  It is impossible to discern until it has occupied a shell.

Saura does not come from underwater locations, although it can come from water itself.  The reasons why elude researchers, but one hypothesis is that land lifeforms tend to be more similar to one another than underwater lifeforms, and that, should Maquette ever extend to touch other worlds where dominant lifeforms reside exclusively underwater, there will be new ‘lockettes’ in the vein of dexettes.  Others contend that other underwater lifeforms might simply be similar enough to dexettes to be folded in with them.

Saura is not fully aware.  While it has the capacity to become a fully-fledged lockette, it does not possess true reasoning capabilities or significant knowledge of the universe.  It is believed that it either innately is aware of the common tongue of Maquette, or that this is imparted upon it somehow.  (Believers from any of the sects that follow the Artist would claim this is due to the Loom, but this has never been proven).

Saura does not possess the capacity to differentiate between suitable shells and unsuitable shells, between shells that are guarded and shells that are unguarded.  While it will generally seek out a more or less humanoid shell, there are occasional reports of saura taking other ‘shells’, such as the infamous spell jars, or even the reports of a shell made in the shape of a wolf from Earth.  These are extremely unusual cases, and some, such as the wolf-lockette, are generally believed to be urban legends.

Saura is not able to survive long-term without replenishment of some form.  While researchers are unsure how it replenishes itself without having inhabited a shell, it has been occasionally observed to stay still for long periods of time before moving on in search of a shell.  For a manifested lockette, there are plenty of ways to replenish saura, such as eating, use of their summons, or sleep, which are all strategies different lockettes employ to varying degrees - some may eschew one entirely.  (There is also saura sharing, or, for the possessed, saura theft, but that is something of a different matter).

Beyond this, little is truly known.