If life developed on a planet which wasnt very rich in iron what could could be used as a suitable subsitute for it? And would this difference in metal restrict these lifeforms to any constraints??

is it necessary that the "aliens" or "ET" we are looking for necessarily carry the same body functions like we do? we are carbon based maybe they could be something entirely different. (question  comes coz in a newspaper article i read that we should be  looking for "earth like planets".)

Respected

What if aliens attacked on earth ? I know there two possibilites that will they attack or friends? Let's take one point of view, if they attack what will be the way they choose to  attack and where and how ? and the damage

Suppose I want to leave an artifact for future/alien civilizations to find.  Putting "Built 2010" isn't much use without external references.  Is there a method of telling a future archeologist the age of this object.

These photos were taken in my parent's garden, Gloucestershire, during the snowy weather in January earlier this year.

The first photo shows the footprints starting near to the back door of their house, the second shows them making their way past the side of the house in a very straight line and the final photo shows them simply stopping.

We're still all very puzzled and wondered if anyone had any theories or ideas?