Last fall I noticed what I thought was a smashed bird in my driveway. A few time I tried moving with my foot but it never moved. Today I was washing the driveway and I tried to force water in the hole. Lots of 'fluff' just kept coming out. I decided to stop and find out what is going on. There is another spot that looks the same. What is it? Should I pull it all out and seal the spot? Will this keep happening? I hope you can help. Thanks.