It is a fossil fuel in that it is formed under the right pressure and temperature from primarily dead algae preserved in the bowels of the oceans. Most plant and animal life that die in the ocean are consumed by bottom feeders but under anoxic (no oxygen) conditions, it is accumulated, buried, and thermally cracked with the earth being the refinery. Voila, oil and gas. It takes a long time for significant amounts to form but it subsequently needs to be concentrated in a trap to be of commercial use to us. There are droplets of oil all beneath the surface just as there are a few grains of gold in your backyard. The oil eventually makes it to the surface if it is not trapped.
Yes - The La Brea tar pits, the oil sands in Canada, and oil shale in Utah are all examples.
Off the top of my head, I recall that an astounding percentage - like 80% - of the earth's permeable oil has already reached the surface.
Most of it has dissolved, evaporated, or been consumed by micro organisms.
you need to get out and read some more, The russians have been saying for years and with great success, that OIL IS ABIOTIC and A Renewable Energy created by Compressed Minerals in the earths crust, It has absolutely Zilch to do with ALGAE, or FOSSILS.