type II disks on the hull

[LanMorehell]

Good day everyone!

Please help me to understand what are these strange disks on both sides of the hull are for and, subsequently, what color were they?

I am building a type II model and wondering whether i should paint these circles in different color.

Thanks!

[Buddahaid]

I think those are hydrophone sound heads. I haven't found any images like yours yet but there is a museum ship in Finland.
Submarine Vesikko.