A while back I discovered a brown "blob" floating in the pond. When I scooped it out it broke apart had a terrible smell. Thought it was an old dead fish. Now a month or so later I am finding them all over my 1/2 acre pond. Some the size of a mouse, others the size of a squirrel. They just break apart and there is nothing solid to them (i.e. no bones). It's like a "skin" covering a brown blob of goo that really stinks when it breaks apart.

Any ideas?