Things in the astral plane aren't as simple or safe as one might think. Here's some reasons
1) The Astral Plane reflects Real-Life, so what happens there, somewhat effects here.
2) There are different creatures roaming the astral plane.
3) The laws of physics generally apply, but there are cases that they don't.
4) In the astral plane, sometimes animals aren't really animals. It's best to avoid anything suspicious.
5) Magick has less limits in the astral plane, so beware!
There are ways of keeping safe from things in the astral realm, these are a couple ways.But they don't protect against everything.
1) Wear an amulet thats blessed in the physical realm.
2) Make a circle of salt around you in physical.
3) Avoid anything that breathes.
4) Wield a weapon in the physical realm. It will or should, project with you.