Strange algae (?) in my sump

[Dash]

Thanks H2o2, I think you got it.
Neomeris annulata, or finger algae. Many report it as invasive (thrives in SPS tanks). As it’s calcareous, nothing will eat it. It also is inefficient at nutrient export so is useless in the sump. Since it spreads by fragmentation/sporulation, I think it’s best to remove the rock. Luckily it’s just a small random one that I tossed in the sump for the pods so no big deal.
Weird that it requires calcium to grow & I don’t dose anything. Apparently some people want it in their aquariums, in which case it’s recommended to supplement calcium. If anyone wants this, they’re welcome to it, haha