I don't think fish eggs are laid in clumps, but rather are sprayed out into the nest as single eggs (although in mass numbers).
Are you sure they weren't frog eggs, or some Bryozoa ( http://www.co.thurston.wa.us/health/...df/bryozoa.pdf )
I don't think Crappie eat eggs of other fish, as a rule, but I wouldn't put it past them :p
The fact that you said you were fishing a "large deadfall tree", makes me think that's the single biggest reason for the amount of fish there. That's especially true if the tree is extended out into relatively deep water. And it's a "normal" place to find Bryozoa colonies.
If it should happen to be Bryozoa ... take heart ... that's a very good sign that the water is in good shape. They don't do well in polluted waters.
... cp