The Bone Goo Ball is extremely resilient. It cannot be destroyed by spikes, so you can use it protect other balls.
<ball name="Bone" shape="rectangle,50,50" mass="60" towermass="4.0" strands="2" walkspeed="0.1" walkforce="3000" climbspeed="0.9" speedvariance="0.2" jump="0.0,0.3" sticky="false" blinkcolor="0,0,0" invulnerable="true" grumpy="false" hingedrag="false" attenuationselect="0.05, 1.0, 1.2" attenuationdeselect="0.05, 1.2, 1.0" attenuationdrop="0.05, 1.2, 1.0" attenuationdrag="0.05, 1.2, 1.0" maxattachspeed="1000" material="BoneBall" jumponwakeup="false" staticwhensleeping="true" > <marker drag="IMAGE_BALL_BONE_DRAGMARKER_P1" detach="IMAGE_BALL_BONE_DETACHMARKER_P1" rotspeed="2" /> <shadow image="IMAGE_BALL_BONE_SHAD"/> <particles id="sleepyZzz" states="sleeping" overball="true" /> <strand type="spring" image="IMAGE_BALL_BONE_STRAND" inactiveimage="IMAGE_BALL_BONE_STRAND" springconstmin="10" springconstmax="10" dampfac="0.9" maxlen2="120" maxforce="800" minlen="100" thickness="20" walkable="false" /> <detachstrand image="IMAGE_BALL_BONE_DSTRAND" maxlen="60" /> <splat image="IMAGE_BALL_BONE_SPLAT1,IMAGE_BALL_BONE_SPLAT2"/> <part name="jaw" layer="0" rotate="true" x="0" y="-25" image="IMAGE_BALL_BONE_JAW" stretch="24,1.5,0.75" scale="0.76" state="climbing,attached,walking,falling,dragging,detaching,standing,tank,sleeping,stuck,stuck_attached,stuck_detaching" /> <part name="body" layer="1" rotate="true" x="0" y="0" image="IMAGE_BALL_BONE_BODY1,IMAGE_BALL_BONE_BODY2" stretch="24,1.5,0.75" scale="0.75" /> <sound event="drop" id="SOUND_BALL_GENERIC_MUMBLE1,SOUND_BALL_GENERIC_MUMBLE2,SOUND_BALL_GENERIC_MUMBLE3,SOUND_BALL_GENERIC_MUMBLE4,SOUND_BALL_GENERIC_MUMBLE5,SOUND_BALL_GENERIC_MUMBLE6,SOUND_BALL_GENERIC_MUMBLE7"/> <sound event="throw" id="SOUND_BALL_GENERIC_MUMBLE1,SOUND_BALL_GENERIC_MUMBLE2,SOUND_BALL_GENERIC_MUMBLE3,SOUND_BALL_GENERIC_MUMBLE4,SOUND_BALL_GENERIC_MUMBLE5,SOUND_BALL_GENERIC_MUMBLE6,SOUND_BALL_GENERIC_MUMBLE7"/> <sound event="bounce" id="SOUND_BALL_GENERIC_BOUNCE1,SOUND_BALL_GENERIC_BOUNCE2,SOUND_BALL_GENERIC_BOUNCE3,SOUND_BALL_GENERIC_BOUNCE4"/> <sound event="land" id="SOUND_BALL_GENERIC_STICK1,SOUND_BALL_GENERIC_STICK2,SOUND_BALL_GENERIC_STICK3,SOUND_BALL_GENERIC_STICK4,SOUND_BALL_GENERIC_STICK5,SOUND_BALL_GENERIC_STICK6"/> <sound event="marker" id="SOUND_BALL_GENERIC_ROLLOVER1,SOUND_BALL_GENERIC_ROLLOVER2,SOUND_BALL_GENERIC_ROLLOVER3,SOUND_BALL_GENERIC_ROLLOVER4,SOUND_BALL_GENERIC_ROLLOVER5,SOUND_BALL_GENERIC_ROLLOVER6,SOUND_BALL_GENERIC_ROLLOVER7,SOUND_BALL_GENERIC_ROLLOVER8"/> <sound event="pickup" id="SOUND_BALL_GENERIC_PICKUP1,SOUND_BALL_GENERIC_PICKUP2,SOUND_BALL_GENERIC_PICKUP3,SOUND_BALL_GENERIC_PICKUP4,SOUND_BALL_GENERIC_PICKUP5,SOUND_BALL_GENERIC_PICKUP6,SOUND_BALL_GENERIC_PICKUP7,SOUND_BALL_GENERIC_PICKUP8,SOUND_BALL_GENERIC_PICKUP9,SOUND_BALL_GENERIC_PICKUP10"/> <sound event="attach" id="SOUND_BALL_GENERIC_ATTACH01,SOUND_BALL_GENERIC_ATTACH02,SOUND_BALL_GENERIC_ATTACH03,SOUND_BALL_GENERIC_STICK1,SOUND_BALL_GENERIC_STICK2,SOUND_BALL_GENERIC_STICK3,SOUND_BALL_GENERIC_STICK4,SOUND_BALL_GENERIC_STICK5,SOUND_BALL_GENERIC_STICK6"/> <sound event="detaching" id="SOUND_BALL_GENERIC_DETACHING1"/> <sound event="detached" id="SOUND_BALL_GENERIC_ATTACH01,SOUND_BALL_GENERIC_ATTACH02,SOUND_BALL_GENERIC_ATTACH03,SOUND_BALL_GENERIC_DETACHED1"/> <sound event="snap" id="SOUND_BALL_GENERIC_SNAP1"/> <sound event="death" id="SOUND_BALL_GENERIC_DEATH1"/> <sound event="suction" id="SOUND_BALL_GENERIC_DETACHED1"/> <sound event="exit" id=""/> <!-- climbing animations --> <sinvariance freq="0.3" amp="0.03" shift="0"> <sinanim part="jaw" state="climbing" type="translate" axis="y" freq="4.0" amp="3" shift="0" /> </sinvariance> <!-- dragging animations --> <sinvariance freq="0.3" amp="0.03" shift="0"> <sinanim part="jaw" state="dragging" type="translate" axis="y" freq="4.0" amp="10" shift="0" /> </sinvariance> <!-- dragging animations --> <sinvariance freq="0.3" amp="0.03" shift="0"> <sinanim part="jaw" state="attached" type="translate" axis="y" freq="4.0" amp="3" shift="0" /> </sinvariance> <!-- tank animations --> <sinvariance freq="0.3" amp="0.03" shift="0"> <sinanim part="jaw" state="tank" type="translate" axis="y" freq="4.0" amp="3" shift="0" /> </sinvariance> </ball>