Day 7 in cycling. What is this??

[Minosimports]

im at day 7 of cycling. Started with live rock, sand and added more bactaria to jump start the process. All is well but today I noticed this hitch hiker.. and a green leaf growing from my rock.???

 

[NY_Caveman]

Picture 1 is small but may be macroalgae if it was live rock. Second picture looks like a sea slug. Maybe a Caulerpa slug.

 

[NY_Caveman]

Check out Caulerpa slug in this link. It is a good herbivore.

https://www.lionfishlair.com/hitchhikers-guide/elysia/