sea mushrooms no where to be found

[indigo ridge]

I have spent an entire in game week trying to find sea mushrooms and I scour the entire ocean for an entire in game week to not find even 1. I have shut down my game several times to attempt to fix this. I need them to make a certain seed for my ocean farm. Please help solve the case of the missing sea mushroom. I am playing on the Xbox x if that helps. Thank you.