From the picture it's not possible to determine how many legs it has or how big it is, so identification from the picture alone is only a guess. It is possible that it is a Tick. Ticks hatch from eggs and develop through three active (and blood-feeding) stages: larvae (small-the size of sand grains); nymphs (medium-the size of poppy seeds); adults (large-the size of apple seeds). If you see them bigger, they're probably partially-full or full of blood.
Following are a few links to websites with more information about Ticks: