I found this today looking for driftwood along the Chesapeake Bay near Baltimore. It is very lightweight, it is definitely fossilized, and the chambers are thin walled and shallow depth-between 1/8 and 1/4 in wide and seem to be generally hexagonal. Initially I thought wasps nest but the size of the chambers isn't uniform, however I do think perhaps it could be a strange colonial Coral but it isn't calcified. I've never found anything like this in Maryland before and I'm having trouble finding others like it online. Any incite is appreciated, thank you.