Something is ribbed if it has a raised pattern on it or markings that look a bit like ribs.
Something is speckled if it is covered in small marks or specks.
The eggs in the picture are speckled.
Something is spotted if it has a pattern of small, round things all over it. Many animals are spotted. If the spots are perfectly round and even they are usually called dots. People will usually call animals covered in dots spotted and clothes covered in spots to be dotted.
Symmetry means that if you draw a line through something, usually down the middle, then the two halves of it are identical but reversed - like looking into a mirror. Things that are symmetrical are usually nice to look at.
People's faces are symmetrical because if you draw a line down the middle of your face the left and right sides are the same. In fact, your entire body is symmetrical, as are animal's faces and bodies. Lots of everyday things are symmetrical. How many symmetrical things can you see around you?
The picture is a shape that is symmetrical along the left and right half and the top and bottom halves.
The opposite of symmetry is asymmetry.
Tabby is a pattern made up of stripes, spots and swirls that is usually seen on cats. It helps them to camouflage so they can sneak up on their prey.