What do you think about crack?

This is a non CC boat. It’s a Carolina Skiff which for those who aren’t familiar its a rolled gunnel boat, the floor is all foam filled and no stringers going lengthwise rather some sort of “4x4 structural foam” block placed every ~18” or so going across the hull and the voids are filled with foam then glassed over making the finished floor. No bilge. Are these super fine cracks on the floor superficial or would that be signs of the foam has swelled with water and cracking the floor? It’s not what I expect for a crack due to swelling wood or foam.

Mushrooms, hands down.