What's this leaf shaped thing?

[Darkcartographer]

This thing has been growing between my sand and aquarium glass. There are two smaller ones like it that I can see. What is it?

 

[Tired]

Poke it with something, see if it reacts at all. I'd guess probably it's unhappy, buried macroalgae.

 

[Darkcartographer]

Poke it with something, see if it reacts at all. I'd guess probably it's unhappy, buried macroalgae.

It looks like it is macroalgae. It just didn't look like any of the ones I had added to my tank. But now that it's starting to grow above the sand it looks more similar to some I added. Thanks!

 

[vetteguy53081]

Its macroalgae possibly a type of ulva

 

[WheatToast]

Various "rooted" calcified macroalgae like Udotea, Penicillus, and Rhipocephalus will send up new, conic shoots like these when their old, dying growth has reached the end of its lifecycle. This is a completely natural process and not an indicator of poor health.