Green plant things.

[jerental]

How do climb them or interact with them?

 

[GarlicJelly]

As far as I know they have never been working. I think it's a work in progress atm or that you aquire the skill (just like the phase ability) later on as you kill another boss. But since the game hasn't come that far yet it's just going to be a teaser that makes you look at that chest in the flying temple expectantly.