4. The Easter Island 'whale' is carved in stone:

The front of the beast has a greedy mouth and we can see an eye of the sort which can be interpreted as 'water' (by cause of the double rim). I suggest this front represents spring and that the watery eye says that Sun has not yet returned, i.e. the front indicates the early spring season.

The tail end of the beast (at right in the picture below) is designed as a skull of death:

My interpretation is that Sun here has changed into an 'old bone'. The beginning is eating, eating, eating, but the end is death.

The top of the tail end has a 5-sided hole (see at left in the picture above) which could represent an earth oven (umu). This hole, I guess, corresponds to the head of Cetus:

The watery eye of the stone beast suggests its location is below the midline of the sky roof.

If we reverse the season of Cetus north of the equator to the simultaneous season south of the equator - from heliacal rising in the 3rd right ascension hour in the 2nd quarter after winter solstice to a heliacal rising in the 2nd quarter after summer solstice, then the Cetus season could be a sign of Sun descending into the 'sea' rather than the monster climbing back on land.

Instead of the head of Cetus emerging from the 'sea' we ought to see the head of Cetus changed into a death skull. The position below the pentagonal outline could have been necessary in order to submerge the 'old bone'. And the front of the stone beast cannot be above the surface either, which explains the watery eye (it is unclear if there is a single eye or two of them).