Ayuda por favor 10 errores en la puntuacion y en los verbos?

I am a scientist and I work at a laboratory.

Last Monday, I found a cave in the mountain.

It was dark, but I saw a light at the back of the cave.

There was a huge egg!

That evening I showed the other scientists.

We thought perhaps it was a dinosaur´s egg, so we were very excited.

We believed the egg was safe.

That night, we were all in bed when the fire alarm rang, but there was no fire!

So, who rang the alarm?

Next day I found a lot of paint on our car.

We couldn´t drive it !

We were shocked.

Meanwhile, in the mountains, more eggs began to open.