I.D. and ?

[zland1]

What is this and should I keep it?
When it’s pulled together it’s about 3inches long & 1/4inches wide I saw it stretch to about 6 inches but I think it can go longer.
Is it safe to leave in tank when that big?

http://img368.imageshack.us/img368/7086/fish05012worm4ze.th.jpg (http://img368.imageshack.us/my.php?image=fish05012worm4ze.jpg)

http://img368.imageshack.us/img368/3809/fish05006worn9yh.th.jpg (http://img368.imageshack.us/my.php?image=fish05006worn9yh.jpg)

Thank You Joe

[HaKs310]

Bristle worm.
Beneficial scavenger.

[romunov]

Size doesn't matter.