Most of the echoes that show no "gap" between the target and the shadow are "stuff" on the bottom - rocks, shells, trash ...
Echoes that show no shadow at all are usually higher in the water column ...causing its shadow to cast upon the bottom farther outside the SI Range selected ...
This diagram shows how targets and their shadow help discern where that target is in relation to the SI view ...
The echoes are elongated because your Chart speed (2) is higher than your boat speed (0.4mph) causing the SI to repeatedly ping the same target over and over ...
Higher Chart speed is not a bad thing ... Sometimes the elongated echoes make it easier to discern what one is seeing ...
Rickie