Bacteria, Detritus, something else

[Dieseltech77]

Can anyone identify the white mass on the photos? Its appears mucosal, and is fairly firmly attached to my Ulva Lactuca. It's only in my fuge and only on the sea lettuce.

 

[vetteguy53081]

Can anyone identify the mass on the photos? Its appears mucosal, and is fairly firmly attached to my Ulva Lactuca. It's only in my fuge and only on the sea lettuce.

Looks like ulva which is similar to sea lettuce
This would be a tangs delight