Map symbols?

[Sabaithal]

Anyone know of a guide or something where I can find out what the map symbols mean? Tried googling it, to no avail. I'm seeing a symbol that looks like crossbones, and have no idea what that indicates.

And on a side note, I've found this weird worm thing near the upper area of the second shelter (where the flying squid things are) with a flashing symbol. I can't reach it, and throwing stuff at it does nothing. What is that?

[hmaAst]

Skull + crossbones: Area where you have died previously
White-yellow flashing circle with X in it: Location of a karma flower (eating them will prevent you from going down a karma level when you die)
Expanding blue circles: Location of batflies

I think what you're describing are the arena unlocks. If you run into the hologram it produces, it unlocks either a creature, item, or arena in sandbox mode.