What is this

[Wrencher]

What is this and how do I get rid of it? Slime algae? New tank, not completely cycled.

 

[CfishGo]

Looks like biofim to me. It will go away.

 

[Aiken Drum]

Its mould. A generally harmless biofilm made up of fungus and bacteria commonly released by new driftwood. Syphon it out, or remove the wood and wipe it off before returning the wood. It will keep coming back, but eventually the mould spores should stop growing back as the decomposing cellulose in the wood that the mould feeds on gets used up. Boiling the wood can help with this process as it will kill off a lot of spores and slow down how quickly it regrows.