What's in a name?

byssus  [bss] noun
a mass of strong silky threads that molluscs such as mussels use to attach themselves to rocks and other hard surfaces.

Hydra  [hdr]
Greek Mythology - a many-headed snake whose heads grew again as they were cut off, killed by Hercules.  [as noun hydra] a thing which is hard to overcome or resist because of its pervasive or enduring quality or its many aspects.

Sources: Encarta World English Dictionary; New Oxford Dictionary of English.